What Is an Opening Line in Sports Betting? The Complete Guide
The opening line is the first odds price published by a bookmaker when a new market becomes available. It represents the oddsmaker's initial assessment of the probability of each outcome, set before any significant betting action has occurred. Opening lines are fundamental to sports betting strategy, particularly in US sports culture where they often appear days before the event and serve as the starting point for all market activity.
Understanding opening lines is essential for both casual and professional bettors. The opening line is not just a static price—it's a snapshot of what the market believes, a signal of where sharp money might be heading, and an opportunity to capture value before the general public places their bets. For serious bettors, the opening line represents the first chance to identify mispriced outcomes and build what's known as closing line value (CLV).
What Is an Opening Line in Sports Betting?
The Definition and Core Concept
An opening line is the initial set of odds or point spread that a sportsbook publishes when a betting market first opens. For most major sports, this happens well in advance of the event—sometimes days ahead. The opening line is the bookmaker's honest first assessment of the matchup, based on statistical models, historical data, and expert judgment about team strength, player availability, and situational factors.
Unlike the closing line (the final odds just before an event starts), the opening line is set with relatively limited betting information. Bookmakers deliberately post opening lines with lower betting limits than they will accept later. This is a deliberate strategy: low limits allow the sportsbook to test market reaction from professional bettors without risking large sums of money if the line is mispriced.
The opening line serves three critical functions:
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Information Discovery: Bookmakers use opening lines to gather information from sharp bettors. If a sharp bettor immediately bets heavily against an opening line, the bookmaker learns that their initial assessment may be wrong.
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Market Signal: The opening line tells the betting market where the sportsbook believes the true probability lies. It's the first public statement of the oddsmaker's position.
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Betting Opportunity: For professional bettors, the opening line represents the first chance to place a wager at what might be the most favorable price before public money arrives.
Why Opening Lines Matter
Opening lines matter because they are the starting point for all market dynamics. Once an opening line is published, three things happen: sharp bettors evaluate it for value, the general public eventually bets on it (usually closer to game time), and the line moves in response to this action.
The opening line is particularly important in US sports betting culture because of the concept of sharp bookmakers. A handful of elite sportsbooks—historically including offshore operations and more recently Circa Sports in Las Vegas—set the opening lines that the rest of the industry follows. These sharp books have superior pricing models and risk management, so their opening lines are considered the most accurate in the market.
When a sharp bookmaker opens a line, other sportsbooks monitor it closely. If the sharp book opens a game at -3, other books will typically open at or very close to -3. This happens because of arbitrage: if one book opens at -3 and another at -2.5, arbitrageurs (bettors with no opinion on the game) will immediately bet both sides and lock in a risk-free profit. To prevent this, books stay tightly aligned on opening lines.
The opening line also matters because it often represents the best price for underdogs. This is a critical insight for value-oriented bettors. Because the general public overwhelmingly bets on favorites and popular teams, the favorite's odds tend to shorten (get worse for bettors) as the event approaches, while underdog odds lengthen (improve for bettors). Therefore, underdogs are often available at their best prices at the opening line, before public money arrives to push the odds in the opposite direction.
When Do Opening Lines Get Released?
The timing of opening lines varies significantly by sport and betting market:
NFL and College Football: Opening lines typically release on Sunday evening for the following week's games. This gives bettors a full week to evaluate the line, track movement, and place their bets. The Sunday evening release is known as the "overnight line" and is when sharp bettors begin their evaluation.
NBA and NHL: These sports feature daily games, so opening lines typically release the night before (the "overnight line") or early morning of the game day. Some sportsbooks release opening lines for the entire week ahead.
MLB: Baseball opening lines release either the night before games or early in the morning. Pitching matchups, which can change, often influence when lines are released.
Other Sports: Tennis, golf, boxing, and other sports release opening lines on varying schedules depending on the event schedule and when key information (like participant confirmation) becomes available.
The timing of opening line releases is strategic. Sharp bettors wake up early or stay up late to catch opening lines before they move. If you're betting the opening line, timing matters immensely—a line that's available at opening might be gone or significantly moved within hours.
How Do Bookmakers Set Opening Lines?
The Role of Oddsmakers and Mathematical Models
Setting an opening line is both an art and a science. Bookmakers employ oddsmakers (also called pricing analysts or line makers) who use sophisticated statistical models combined with expert judgment to determine the opening line.
The mathematical foundation of opening lines begins with probability estimation. For a football game, an oddsmaker might estimate that Team A has a 55% probability of winning and Team B has a 45% probability. The oddsmaker then converts these probabilities into odds or point spreads that reflect these estimates while also accounting for the vigorish (the bookmaker's commission).
The factors that go into opening line calculation include:
| Factor | Impact | Example |
|---|---|---|
| Team Strength (Elo, Power Ratings) | Primary | Team A's strength rating vs. Team B's |
| Home/Away Advantage | 2-3 points in most sports | Home teams typically favored |
| Injury Reports | Variable | Loss of star player could shift line 1-3 points |
| Weather Conditions | Sport-dependent | Wind/cold in football, heat in tennis |
| Historical Matchups | Moderate | Head-to-head records and trends |
| Rest Differential | Variable | Days off between games for each team |
| Public Sentiment | Moderate | How popular teams might attract public money |
| Situational Factors | Variable | Revenge spot, motivation, schedule position |
| Pace of Play | Moderate | Fast-paced teams vs. defensive teams |
| Regression to Mean | Statistical | Teams performing above/below expectation |
Modern oddsmakers use proprietary models that weight these factors differently. Some books emphasize historical performance, others focus on current form. The best oddsmakers—those at sharp sportsbooks—have models that are extremely well-calibrated and regularly tested against closing lines to ensure accuracy.
The Historical Evolution of Opening Lines
The history of opening lines reveals how the betting market has evolved and who holds the power to set prices.
The Las Vegas Era (1960s-1980s): In the early days of modern sports betting, Las Vegas was the center of the betting universe. A legendary oddsmaker named Bob Martin, working at Churchill Downs and later the Plaza Hotel in Las Vegas, became famous for setting the "Las Vegas Line." This line was disseminated across the country and became the de facto market standard. Regional sportsbooks would adjust Martin's line based on anticipated local action, but the Las Vegas Line was the anchor.
The LVSC Era (1980s-1990s): As sports betting grew, Roxy Roxborough and his company Las Vegas Sports Consultants (LVSC) became the dominant line-setting authority. LVSC provided opening lines to sportsbooks across the country, and their lines were widely respected for accuracy. During this period, Las Vegas maintained its reputation as the place where "the line" was set.
The Offshore Migration (1990s-2000s): As the internet rose to prominence and the most talented bookmakers migrated offshore to jurisdictions like Curaçao and Costa Rica, a new breed of oddsmakers emerged. These offshore sportsbooks attracted the sharpest bettors in the world because they offered higher betting limits and more efficient pricing. Offshore shops like Pinnacle (now Pinnacle Sports) became the new standard-setters. The volume of money being bet into these lines exceeded what was being bet in Las Vegas, making offshore opening lines the true market benchmark.
The Modern Era (2010s-Present): With the expansion of legal sports betting in the United States, the landscape has shifted again. Circa Sports, which opened in Las Vegas in 2018, has become famous for setting aggressive opening lines that attract professional bettors. Circa's opening lines are widely followed by other sportsbooks. However, offshore sportsbooks and exchanges like Pinnacle continue to set some of the sharpest opening lines due to their superior risk management and customer base of professional bettors.
The key insight from this history: opening lines are set by the most efficient, professional-friendly sportsbooks, not by a central authority. The idea that "Vegas" sets the line is a myth. Instead, a small number of sharp books set opening lines, and the rest of the market follows.
Why Bookmakers Start with Lower Betting Limits
When a sportsbook opens a new line, they deliberately start with lower betting limits than they will accept later. An opening line might have a maximum bet of $500, while the same line later in the day might accept $5,000 maximum.
This strategy serves a critical purpose: information gathering. By starting with low limits, the bookmaker can test how sharp bettors react to the opening line without risking massive sums of money. If a sharp bettor immediately bets $500 against the opening line, the bookmaker learns that the opening line is likely mispriced. This triggers an adjustment.
Once the bookmaker feels confident in the line—either because sharp bettors have validated it or because it's been bet into aggressively from both sides—limits are increased. This signals to the market that the bookmaker is comfortable with the price. Professional bettors who were waiting for higher limits can now place their full-sized bets.
This dynamic explains why opening lines move quickly in the first hours after release. The first bets placed against an opening line are often sharp bettors testing the line. The bookmaker reacts to this information and adjusts. By the time limits increase, the line may already be significantly different from the opening.
Opening Lines vs. Closing Lines: What's the Difference?
Timing and Accuracy
The most important difference between opening and closing lines is timing and information. Opening lines are published days before an event; closing lines are the final odds just before the event starts.
| Aspect | Opening Line | Closing Line |
|---|---|---|
| Timing | Days before event | Minutes before event |
| Information Available | Limited | Complete |
| Betting Action | None yet | All action completed |
| Accuracy | Good estimate | Most accurate |
| Price Quality | Often soft for underdogs | Reflects true market view |
| Limits | Low | High |
| Adjustment Potential | High | Minimal |
Because closing lines incorporate all available information—every injury report, every weather update, every piece of news—they are more accurate than opening lines. This is a fundamental principle of market efficiency: more information leads to better prices.
Research on closing line accuracy consistently shows that closing lines are better predictors of actual outcomes than opening lines. A study comparing opening and closing lines in NFL games found that closing lines outperformed opening lines in predictive accuracy by a measurable margin. This makes intuitive sense: the closing line has seen a week of betting action, news flow, and market discovery, while the opening line is an initial guess.
What Causes Line Movement Between Opening and Closing?
Line movement—the change from opening line to closing line—is caused by several factors working together:
Betting Action: The primary driver of line movement is the flow of money. If one side of a bet receives significantly more action than the other, the bookmaker will adjust the line to encourage betting on the other side. For example, if 70% of bets are coming in on Team A at -3, the bookmaker will move the line to -3.5 or -4 to make Team B more attractive and balance their liability.
Sharp vs. Public Money: There's a crucial distinction between sharp money and public money. Sharp bettors (professionals with statistical edge) bet early and in large amounts. Public bettors (casual bettors) tend to bet later and favor popular teams. When sharp money hits a line early, it moves quickly. When public money arrives later, the line often moves in the opposite direction.
Information Flow: Injury reports, weather updates, roster changes, and other news cause line movement. If a team's star player is ruled out hours before an event, the line will adjust to reflect this new information.
Arbitrage Activity: When two sportsbooks open different lines, arbitrageurs exploit the difference by betting both sides. This activity forces sportsbooks to align their opening lines, creating movement.
Limit Increases: When a bookmaker increases betting limits, they're signaling confidence in the line. This can trigger additional action and further movement.
A typical NFL line movement looks like this:
- Sunday 6 PM: Opening line released at Team A -3
- Sunday 11 PM: Sharp bettors hit Team A heavily; line moves to -3.5
- Monday-Thursday: Mixture of sharp and public action; line fluctuates between -3.5 and -4
- Friday: Public money arrives on Team A (the favorite); line moves to -4.5
- Sunday 1 PM (closing): Final line at -4.5, reflecting all action
This movement pattern—opening soft on the favorite, then moving toward the favorite as public money arrives—is extremely common.
Which Should You Bet: Opening or Closing?
This is the most practical question in sports betting strategy, and the answer depends on your skill and edge.
The Case for Betting Opening Lines: If you have identified genuine value in an opening line—meaning you believe the probability is better than what the line reflects—then betting the opening line before public money arrives is advantageous. You get the best price, and you capture what's called closing line value (CLV).
The Case for Betting Closing Lines: If you don't have a strong edge or analytical system, betting the closing line is safer. The closing line is more accurate, so you're betting into a more fairly-priced market. You won't get the best price, but you won't get a terrible price either.
The Professional Approach: Serious bettors focus on closing line value. They evaluate opening lines, look for mispricings, and bet the opening line when they find value. They then track their results against the closing line to see if they're beating the market. Over time, positive closing line value is the metric that separates winning bettors from losing ones.
For most casual bettors, the practical advice is: don't rush to bet the opening line. Wait until you see some line movement and understand the market's reaction. If you spot value at the opening line, take it. But if you're unsure, waiting is fine—you'll still have plenty of time to place your bet.
Closing Line Value (CLV) and Opening Line Strategy
What Is Closing Line Value?
Closing line value (CLV) is a measure of how well you did on a bet compared to the closing line. It's the difference between the odds you bet at (your opening line bet) and the odds when the market closed.
Here's a simple example:
- You bet Team A at +2.5 (opening line) for $100
- The closing line is Team A at +1.5
- You got +2.5 when the closing line was +1.5
- You achieved positive CLV of 1 point
This 1-point advantage might seem small, but in point spread betting, a half-point is valuable. Over hundreds of bets, consistent positive CLV is the difference between winning and losing.
CLV is calculated differently depending on the bet type:
Point Spread CLV: Simply the difference in points. If you bet at -3 and the closing line is -4, you have +1 point of CLV (you got a better price).
Moneyline CLV: Calculated using odds. If you bet at -110 and the closing line is -120, you got better odds and have positive CLV.
Over/Under CLV: The difference in the total. If you bet the Over at 45.5 and the closing line is 44.5, you have +1 point of CLV.
How Professional Bettors Exploit Opening Lines
Professional bettors have a systematic approach to opening lines:
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Monitor Opening Lines: Sharp bettors wake up when opening lines release. They immediately evaluate whether the opening line represents value compared to their own probability estimates.
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Identify Mispricings: If their model suggests Team A should be -3.5 but the opening line is -3, they've found value on the underdog. They place a bet.
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Track Line Movement: As the line moves throughout the week, professional bettors monitor the movement to understand what the market is learning. If the line moves toward their position, that's confirmation. If it moves against them, they reassess.
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Build CLV: By betting the opening line when they have identified value, professionals capture CLV. Over a season or year, their positive CLV compounds into significant profit.
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Measure Results Against Closing Line: Professionals track their opening line bets against the closing line to quantify their edge. If they consistently beat closing lines, they're doing something right.
The key insight: professional bettors don't bet randomly at opening lines. They bet opening lines when they've identified value that the market hasn't yet priced in.
Real-World Example: NFL Point Spread
Here's a concrete example of how opening line strategy works in NFL betting:
The Setup: An NFL game opens on Sunday evening with the home team at -3 (-110). A professional syndicate has spent all week building statistical models of both teams. Their model suggests the home team should be -3.5 (55% win probability).
The Evaluation: The opening line of -3 is softer (better) than their model estimate of -3.5. They see value on the home team. However, they also notice that public sentiment is heavily favoring the home team (it's a popular team, playing at home). They predict that public money will arrive during the week, pushing the line toward -4 or -4.5.
The Decision: The syndicate places a $50,000 bet on the home team at -3. This is their opening line bet.
The Week Unfolds:
- Monday: Sharp money continues hitting the home team; line moves to -3.5
- Tuesday: Mixed action; line stays at -3.5
- Wednesday: Public money arrives on the home team; line moves to -4
- Thursday: More public money; line moves to -4.5
- Sunday morning (closing): Final line is -4.5
The Result: The syndicate bet at -3 and the closing line was -4.5. They captured 1.5 points of positive CLV. If the home team wins by 4 points, they win their bet. If the home team wins by 3 points, they win their bet. The closing line would have lost (it was -4.5, so the home team needed to win by 5 to cover). This is the power of CLV—they got a better price and had a higher probability of winning.
Over a season, a professional syndicate might capture dozens of CLV opportunities like this, resulting in substantial profit.
Common Misconceptions About Opening Lines
"Vegas Sets All Opening Lines"
One of the most persistent myths in sports betting is that "Vegas" sets all the opening lines. This is false. Vegas is not a unified entity that sets lines. Instead, a small number of professional sportsbooks set opening lines, and the rest of the market follows.
Historically, Las Vegas was the center of line-setting. But today, the most influential opening lines come from sharp sportsbooks and exchanges, which may or may not be in Las Vegas. Circa Sports in Las Vegas sets influential opening lines, but so do offshore sportsbooks like Pinnacle and various betting exchanges.
The reason people say "Vegas sets the lines" is that Las Vegas was historically the center of professional betting, and the terminology stuck. But the reality is that the market sets the lines through the interaction of sharp bettors and professional bookmakers.
"Opening Lines Are Always the Most Accurate"
This is backwards. Closing lines are more accurate than opening lines because they incorporate more information. Opening lines are a starting estimate; closing lines are the final market verdict after all information has been processed.
This misconception likely arises because opening lines are often quoted as "the line" in media coverage. But media coverage doesn't mean accuracy. It means visibility.
"You Should Always Bet Opening Lines"
This is a dangerous misconception. You should only bet opening lines if you have identified value. Blindly betting opening lines without edge identification is a losing strategy.
The correct principle is: bet when you have identified value, regardless of whether it's the opening line or closing line. Sometimes the opening line is the best price; sometimes it's not. Your job as a bettor is to identify when you have an edge.
The Psychology and Market Dynamics of Opening Lines
Why Sharp Bettors Target Opening Lines
Sharp bettors prioritize opening lines for three reasons:
1. Information Asymmetry: At the opening line, sharp bettors have an information advantage. They've spent weeks analyzing teams, building models, and preparing. The general public hasn't done this work. Sharp bettors can exploit this advantage by identifying mispricings before the public arrives.
2. Lower Limits: Opening line limits are low, but they're still meaningful. A professional bettor with a $1 million bankroll might only be able to bet $500 on the opening line, but they can place multiple bets across sportsbooks. By the time limits increase, they've already captured their position.
3. Softer Lines: Opening lines are often softer (worse for the sportsbook) than closing lines because the bookmaker hasn't yet gathered information from sharp action. This creates opportunity.
Public Money vs. Sharp Money
Understanding the difference between public and sharp money is essential to understanding opening line dynamics.
Sharp Money: Professional bettors with statistical edge, betting large amounts, betting early, and typically favoring underdogs and unders (because these are mispriced by the public).
Public Money: Casual bettors betting small amounts, betting late, and typically favoring favorites and popular teams.
The typical pattern is:
- Opening line: Reflects the oddsmaker's estimate
- Sharp action: Hits the opening line; if sharp bettors disagree with the oddsmaker, they bet heavily on the undervalued side
- Line adjustment: The bookmaker adjusts the line to balance sharp action
- Public arrival: Days later, casual bettors arrive and bet heavily on favorites and popular teams
- Closing line: Reflects the combined action of sharp and public money
This pattern explains why underdogs are often best-priced at the opening line. Sharp bettors see value on the underdog, bet heavily, and the bookmaker adjusts. By the time the public arrives and bets on the favorite, the underdog line has already moved.
The Role of Arbitrage
Arbitrage (or "arbing") is the practice of betting both sides of a market to lock in a risk-free profit. Arbitrage opportunities arise when different sportsbooks open different lines.
For example:
- Book A opens Team A at -2.5
- Book B opens Team A at -3.5
An arbitrageur can bet Team A at -2.5 on Book A and Team B at +3.5 on Book B, locking in a small profit regardless of the outcome.
Because arbitrage opportunities are risk-free, they're quickly exploited. This forces sportsbooks to align their opening lines. If one book opens at -2.5 and another at -3.5, the first book's opening will be bet heavily by arbitrageurs, triggering an adjustment. Within minutes, the lines converge.
This is why most sportsbooks' opening lines are very similar. The market forces them to be aligned to prevent arbitrage. The only time you see significant differences is when one book is deliberately opening a "soft" line to attract action or test the market.
Sport-Specific Opening Line Strategies
NFL and College Football
Football is the most popular sport for opening line betting in the United States. Opening lines for NFL games release on Sunday evening for the following week's games. College football lines also release on Sunday evening.
The week-long window between opening line and game time is significant. It allows time for:
- Injury reports to emerge
- Weather forecasts to develop
- Public sentiment to build
- Sharp bettors to evaluate and place bets
| Sport | Opening Release | Timing | Key Variables |
|---|---|---|---|
| NFL | Sunday 6 PM | 7-8 days | Injuries, weather, motivation |
| College Football | Sunday 6 PM | 7-8 days | Injuries, weather, rivalry |
| NBA | Night before | 1 day | Rest, travel, injuries |
| NHL | Night before | 1 day | Back-to-backs, injuries |
| MLB | Morning of | Same day | Pitching matchups, weather |
For football, the opening line is particularly important because of the time window. Sharp bettors have days to evaluate, and significant information (injuries especially) can emerge during the week. This creates line movement opportunity.
NBA and NHL
Basketball and hockey have daily games, so opening lines release the night before (the "overnight line") or early morning. This compressed timeline means less time for information to emerge and less time for sharp bettors to evaluate.
However, rest differential and back-to-back games are critical factors in NBA/NHL opening lines. A team playing their second game in two nights will often be underdog, even if they're the stronger team. This creates opportunities for bettors who understand these dynamics.
MLB
Baseball opening lines are unique because pitching matchups can change. A team might have their ace scheduled to pitch, but a sudden injury can change the matchup. Some sportsbooks release opening lines the night before, but hold off on increasing limits until pitching is confirmed.
Weather is also critical in baseball. A day game at Wrigley Field with strong winds can dramatically affect the over/under. Opening lines are often released before final weather forecasts, creating movement potential.
How to Use Opening Lines in Your Betting Strategy
Line Shopping Across Multiple Sportsbooks
The most basic opening line strategy is line shopping: comparing opening lines across multiple sportsbooks to find the best price.
In the era of multiple legal sportsbooks, line shopping is essential. Different books open slightly different lines based on their own models and customer base. A half-point difference in a point spread might seem trivial, but over hundreds of bets, half-points add up.
Here's a practical example:
- You want to bet Team A at the opening line
- Book A opens Team A at -3
- Book B opens Team A at -2.5
- Book C opens Team A at -3.5
You should bet Book B at -2.5 to get the best price. Over a season, consistently shopping for the best line can add 0.5-1 full point of CLV.
Tools like OddsJam, The Action Network, and others make line shopping easier by aggregating opening lines across sportsbooks.
Tracking Line Movement
Successful opening line bettors track line movement throughout the week. By monitoring how a line moves, you learn:
- Where sharp money is going
- When public money arrives
- Whether the market is moving toward or away from your position
- When to place additional bets
If you bet Team A at -3 on Sunday and the line moves to -4 by Thursday, you know that public money is hitting Team A. This confirms that you identified value correctly.
Conversely, if you bet Team A at -3 and the line moves to -2, you know that sharp money is hitting Team B. This suggests the market disagrees with your analysis.
Timing Your Bets
The optimal timing for betting opening lines depends on your edge:
- If you have a strong edge and have identified value, bet immediately when the line opens. This captures the best price and the most CLV.
- If you have a moderate edge, wait a few hours for initial sharp action to settle, then bet. This avoids betting into the first sharp reaction.
- If you're uncertain, wait until limits increase (usually the next day). This signals that the bookmaker is confident in the line.
The key is matching your confidence level to your timing. High confidence = early bet. Low confidence = wait for more information.
The Future of Opening Lines
Technology and Algorithmic Line Setting
The future of opening lines involves increasing automation and algorithmic sophistication. Machine learning models are becoming better at predicting outcomes, and some sportsbooks are experimenting with AI-driven line setting.
However, human judgment will likely remain important. The best opening lines come from a combination of statistical models and expert judgment. An algorithm can process vast amounts of data, but it can't account for every contextual factor (like a team's motivation or a coach's tendency in specific situations).
As technology improves, opening lines will likely become more efficient. This means fewer mispricings and less opportunity for bettors to exploit. The edge in opening line betting will increasingly go to those with superior models and faster execution.
Market Efficiency and the Disappearing Edge
As sports betting markets mature and become more competitive, opening line edges are shrinking. More professional bettors are competing for the same opportunities, and sportsbooks are improving their models.
This trend suggests that future success in opening line betting will require:
- Superior analytical models
- Faster information processing
- Better understanding of market psychology
- Willingness to bet smaller sizes for smaller edges
The days of finding massive value in opening lines are fading. But for bettors with genuine edge, opening lines will remain the first opportunity to capitalize on that edge before the market fully prices in all information.
Example
An NFL game opens on Tuesday with the home team at -3 (-110). A professional syndicate immediately bets the underdog +3, recognising the line as soft. By Friday, the line has moved to -5.5. The syndicate's early bet at +3 has achieved approximately 2.5 points of positive CLV over the closing line — a significant edge on a point spread bet.
In another example, consider an NBA game where Team A (the stronger team) opens as a 4-point underdog because they're playing their second game in two nights. A sharp bettor recognizes that the market has overcompensated for the back-to-back situation. They bet Team A at +4, capturing value. By game time, the line has moved to +2.5, reflecting the market's correction. The bettor has captured 1.5 points of CLV by identifying a mispricing in the opening line that the market corrected during the day.
These examples illustrate the core principle: opening lines represent opportunities for bettors who can identify mispricings before the market corrects them. The opening line is not the final word—it's the first word in a conversation between sharp bettors, the public, and the market. Those who understand this dynamic can use opening lines to their advantage.