Aligning games and sets in determining tennis matches

Under tennis’s rules, the winner of a match is the player who wins the greater number of sets. In the majority of cases, that is also the player who wins the most games, too—but not always. 

Ahead of this year’s Australian Open, a team of game theorists has highlighted a rare but striking fairness problem: a player can win a match on sets while winning fewer games overall than their opponent.

In their research, which appears in the Journal of Sports Analytics, New York University’s Steven Brams, Wilfrid Laurier University’s Marc Kilgour, and King’s College London’s Mehmet Mars Seven analyzed more than 50,000 Grand Slam singles matches played between 1968 and 2024 and found that such game-set discrepancies occur between 3 and 5 percent of the time.

While this represents a small proportion of matches, they can occur at the highest levels of competition. 

For instance, in the 2019 Wimbledon men’s final Novak Djokovic beat Roger Federer in five sets despite Federer winning more games overall (36–32), giving Djokovic the champion’s trophy. 

Despite the infrequency of these outcomes, the researchers argue that when the set winner and the game winner differ, both players have a legitimate claim to victory, so the sport should have a way to resolve it.

The study’s authors say tennis’s governing bodies have an opportunity to consider a change that would make outcomes fairer and reduce the risk of future discrepancies at the highest level. They have dubbed it “The Grand Tiebreak”.

The proposed rules would be as follows:

• Matches would still be played under standard Grand Slam rules (best-of-five sets for men, best-of-three for women).
• Only if the match winner by sets has won fewer total games than the opponent would the players play a Grand Tiebreak to determine the winner.
• The Grand Tiebreak would be played using standard set tiebreak rules, making it familiar to players, officials, and fans.

Using mathematical modeling, the authors estimate mismatches between the set winner and game winner occur in about 5 percent of men’s best-of-five matches and about 3 percent of women’s best-of-three matches. In practice, the overall rate across Grand Slams is lower, largely because early rounds include many uneven match-ups.

However, the historical record is not trivial when it comes to numbers of matches affected, the researchers note. Across Grand Slam singles matches in the Open Era, these amount to hundreds of cases in which the match winner won fewer games overall.

The authors find that this amounts to around a dozen matches per Slam (Australian Open, French Open, Wimbledon, US Open) in which a Grand Tiebreak scenario arises over the course of tournaments. The research also suggests that the issue becomes more relevant as tournaments progress and opponents become closer in ability.

“Tennis has a long and venerable history, so why are we suggesting a rule change now?” they write. “First, tennis has not been immune to rule changes; over the last 50 years, one of the most significant was the tiebreak after a set ties at 6–6.”

“This solved a serious problem of extraordinarily long matches, sometimes lasting more than a day,” they continue. “We think that the 2019 Wimbledon final highlights the problem that the strengths of two players may well be gauged by different and equally valid performance measures. A Grand Tiebreak will force players to try to succeed according to both measures, so its existence is likely to greatly diminish the need for it.”

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