How Does Tennis Betting Work, and What Happens to Your Bet if a Player Retires?

Tennis betting runs on three layers. The match winner (moneyline) asks who wins. Set betting asks for the exact score in sets. Game handicaps and totals work on the individual games — a player "−4.5 games" must win at least five more games than the opponent across the whole match. Almost every tennis market is one of those three, sliced by set.

What makes tennis different is what happens when someone does not finish. A player can retire injured halfway through a match, and there is no single rule for how that settles. For a tour-level match, Pinnacle, MGM's Springfield book and DraftKings' Massachusetts book all pay a pre-match moneyline once the first set is complete. But DraftKings voids the moneyline on ITF, UTR and exhibition matches even after a completed set, where Pinnacle still pays it, and MGM's live rules cancel every undecided in-play bet when a player retires. Same retirement, different outcomes for what looks like the same bet. Read your book's rule before you need it.

Match winner

The simplest market, and the one with the lowest margin at most books. A player at −250 against an opponent at +200 implies 250 ÷ 350 = 71.43% and 100 ÷ 300 = 33.33%, a total of 104.76%. The extra 4.76 points is the book's margin.

There is no draw in tennis. Every match that finishes has a winner, which makes it a clean two-way market.

Best of three versus best of five

The Grand Slam Rule Book sets the format for the four majors: "All men's singles Main Draw matches in Grand Slam Tournaments shall be the best of five (5) sets. All other matches shall be the best of three (3) sets unless otherwise determined by each Grand Slam Tournament." Outside the men's draws at the majors, you should assume best of three unless the event says otherwise.

The format changes the prices, and the arithmetic shows why. Suppose, to keep it simple, a player wins any given set 60% of the time independently of the others.

• Best of three: win 2-0 (0.6 × 0.6 = 0.36) or 2-1 (two orders of the loss, 2 × 0.6² × 0.4 = 0.288). Total 64.8%.
• Best of five: win 3-0, 3-1 or 3-2: 0.6³ × (1 + 3 × 0.4 + 6 × 0.4²) = 0.216 × 3.16 = 68.3%.

More sets give the better player more chances to let the edge show. At a 55% set edge the numbers are 57.5% and 59.3%. Real sets are not independent — fatigue, momentum and injuries all interfere — so treat this as the direction of the effect, not a pricing model. The point for a bettor: a favourite's price at a major's best-of-five should be shorter than the same matchup at a best-of-three event.

Set betting

Set betting pays on the exact score in sets: 2-0 or 2-1 each way in best of three (four outcomes), 3-0, 3-1 or 3-2 each way in best of five (six outcomes). MGM's rules require the full number of sets to be completed; if a player is awarded the match early, all set betting on that match is cancelled.

Deciding-set tie-breaks count as a set. MGM treats a "Match Tiebreak" played instead of a final set as one set for set markets and one game for game markets: a 6-0, 0-6 match settled by a match tie-break is a 2-1 in sets and 13 total games.

Game handicaps and totals

Game handicaps count every game across the match. MGM's own example: a player given +3.5 games who loses 7-6, 7-6, 7-6 still wins the handicap, because 21 games to 18 is only a three-game margin.

A worked example going the other way. Player A is −4.5 games. The match finishes 6-3, 4-6, 6-2 to A.

• A's games: 6 + 4 + 6 = 16. B's games: 3 + 6 + 2 = 11.
• Margin: 16 − 11 = 5, so A −4.5 covers, even though A lost a set.
• Total games: 16 + 11 = 27. Over 22.5 wins; under 22.5 loses.

Totals are driven heavily by how often the server holds. When holds are routine, sets go to 6-4, 7-5 and tie-breaks, and the total climbs. When breaks are frequent, 6-2 and 6-1 sets pull it down. That is where the surface enters.

Surfaces

The same two players can produce a different match on a different surface. Fast courts and grass reward big serves and tend to produce more holds and more tie-breaks; slow clay extends rallies and makes breaking serve easier. The practical effects for betting are in totals and game handicaps more than in the match price: a clear favourite on clay may still win, but by a different game margin.

Two rulebook notes. DraftKings does not void bets because a match moves indoor to outdoor or changes surface, and MGM says all bets stand in the event of a change to playing surface or venue. The surface you priced is not guaranteed to be the one they play on.

Retirements: the rule that matters most

Here are three sets of published pre-match rules, side by side, for a match where Player A leads 6-4, 3-1 and Player B retires.

Market	Pinnacle	MGM Springfield (MA)	DraftKings (MA)
Moneyline on A	Action: A wins (one set completed)	Action: A wins (first set completed)	Action: A wins at ATP, WTA and Grand Slam level; void in ITF, UTR and exhibition matches
Set betting A 2-0	Void (period not complete)	Cancelled (full sets not completed)	Void
A −3.5 games	Void	Cancelled unless already determined	Void unless already determined
Over 19.5 games	Void	Cancelled unless already determined	Void unless already determined

Bets placed in-play are different at MGM: its live rules cancel all undecided bets on a retirement, so a moneyline on A bought during the match is refunded rather than paid.

Why is over 19.5 void here? At 6-4, 3-1 there have been 14 games. The fastest possible finish is A taking three straight games for 6-4, 6-1 — 17 games. The over was not yet certain, so it voids.

Change the score and it can settle. MGM's rules use the case of a match abandoned at 6-4, 4-4: any finish needs at least two more games, so the match would have reached at least 20 games. Over 19.5 is already a winner and under 19.5 a loser, and the book settles them.

The rules for a walkover — a player withdrawing before the first point — are simpler: DraftKings voids all bets on that match, and MGM cancels them too.

This is the single most important thing to check before betting tennis at a new book, because two bets that look identical on screen can be graded differently. The Academy's guide to settlement rules for overtime and retirements covers how to read those clauses, and sportsbook house rules covers where to find them.

What this means if you bet both sides

If you ever hold opposite positions at two books — a hedge, or an arbitrage — the retirement rules can break the position. Take an ITF match, with A to win at Pinnacle and B to win at DraftKings. B retires after a set: your A bet wins at Pinnacle, your B bet is voided at DraftKings, and you come out ahead. Reverse it — A retires — and your A bet loses at Pinnacle, which settles, while the B bet is voided at DraftKings, which does not. You lose the A stake with nothing on the other side. Mismatched rules turn a hedged position into a one-sided one.

Before you bet tennis

Know the format (best of three or five), know which way the surface pushes the games, and know your book's retirement clause by heart. The next guide in this series applies the same settle-or-void questions to fights: how UFC betting works.