Aligning Games and Sets in Determining Tennis Matches Raises New Fairness Questions

Under the official rules of tennis, the winner of a match is decided by sets, not by the total number of games won. Most of the time, this feels intuitive and fair. The player who wins more sets usually also wins more games along the way. But as new research shows, that alignment does not always hold—and when it breaks, it raises an interesting and uncomfortable question about fairness in one of the world’s most established sports.

A recent academic study by game theorists from New York University, Wilfrid Laurier University, and King’s College London highlights a rare but meaningful scoring anomaly in professional tennis. Their research shows that a player can legally win a match by sets while actually winning fewer games overall than their opponent. While this outcome is uncommon, it happens often enough to deserve serious attention, especially at the highest levels of competition.

How Tennis Scoring Creates the Problem

Tennis uses a hierarchical scoring system. Points make up games, games make up sets, and sets determine the match winner. Crucially, winning a set does not require winning a majority of the games by a large margin. A 6–0 set and a 7–6 set both count as one set, even though the number of games won differs significantly.

Because of this structure, it is possible for one player to dominate certain sets while narrowly losing others, leading to a situation where the set winner is not the game winner. The rules, however, only recognize sets when declaring the winner of a match.

The researchers analyzed more than 50,000 Grand Slam singles matches played between 1968 and 2024, covering the entire Open Era of tennis. Their findings show that mismatches between the set winner and the game winner occur in approximately 3% to 5% of matches, depending on the match format.

How Often Does This Really Happen?

According to the study’s statistical modeling:

In men’s best-of-five matches, the discrepancy appears in about 5% of cases.
In women’s best-of-three matches, it occurs in about 3% of cases.

The overall percentage across Grand Slam tournaments is slightly lower. This is largely because early rounds tend to include mismatched opponents, where dominant wins reduce the likelihood of such anomalies. However, as tournaments progress and player skill levels converge, the probability increases.

Historically, these percentages translate into hundreds of matches in which the official winner won fewer total games than the loser. The researchers estimate that across a single Grand Slam tournament, this situation arises in roughly a dozen matches over the course of the event.

A High-Profile Example: Wimbledon 2019

One of the most famous examples occurred during the 2019 Wimbledon men’s singles final, a match that is already etched into tennis history for other reasons. Novak Djokovic defeated Roger Federer in five sets to claim the championship. However, Federer won 36 games, while Djokovic won only 32.

Despite Federer winning more games overall, Djokovic won more sets and therefore lifted the trophy. Under the current rules, the outcome was perfectly valid. From a broader performance perspective, though, the result feels counterintuitive—and that is exactly the kind of case the researchers are concerned about.

Why Both Players Can Claim Victory

The authors argue that when such discrepancies occur, both players have a legitimate claim to being the better performer. One succeeded in winning the required number of sets, while the other demonstrated greater consistency across the match by winning more games.

This does not mean the existing system is broken, but it does suggest that tennis sometimes measures success using two different and equally reasonable metrics. When those metrics disagree, the sport currently has no mechanism to resolve the conflict.

Introducing the “Grand Tiebreak”

To address this issue, the researchers propose a simple and targeted solution they call the Grand Tiebreak. Importantly, this proposal does not seek to overhaul tennis scoring or interfere with the vast majority of matches.

Under the proposed system:

Matches would continue to follow standard Grand Slam rules: best-of-five sets for men and best-of-three sets for women.
A Grand Tiebreak would only be played if the player who won the match by sets ended up winning fewer total games than their opponent.
The Grand Tiebreak would use standard tiebreak rules, making it familiar to players, officials, and fans.

In other words, the additional tiebreak would act as a rare tie-resolution mechanism, not a routine feature of matches.

Why the Researchers Think This Works

Using mathematical modeling, the authors suggest that simply knowing a Grand Tiebreak could be triggered would influence player behavior. Players would be incentivized to perform well not only in decisive moments that swing sets, but also across every game.

Ironically, this could mean the Grand Tiebreak would almost never be needed. Its existence alone might reduce strategic behaviors that lead to extreme game-set imbalances, much like how the introduction of the standard set tiebreak reduced marathon matches without needing to be used constantly.

Tennis Has Changed Before

One of the most compelling arguments made by the researchers is that tennis is no stranger to rule changes. Over the past 50 years, the sport has introduced:

The set tiebreak at 6–6, which dramatically shortened matches
Changes to final-set tiebreak rules across Grand Slam tournaments
Adjustments to serve clocks, coaching rules, and replay technology

These changes were once controversial but are now widely accepted. The Grand Tiebreak, the authors argue, would be another evolutionary step—one aimed not at convenience or entertainment, but at competitive fairness.

Broader Implications for Sports Analytics

This research also highlights how sports analytics and game theory can uncover hidden issues in long-established systems. Tennis scoring has been in place for over a century, yet large-scale data analysis was needed to quantify how often these paradoxical outcomes occur.

The issue resembles a statistical phenomenon where aggregated results conflict with subgroup outcomes. In tennis terms, sets and games sometimes tell different stories about who performed better.

What Happens Next?

At present, there is no indication that tennis’s governing bodies plan to adopt the Grand Tiebreak. However, the study arrives at a time when tennis is already open to experimentation and modernization, particularly in Grand Slam events.

The researchers believe that governing bodies now have an opportunity to at least consider whether the current system fully reflects competitive fairness, especially in high-stakes matches watched by millions around the world.

Whether or not the Grand Tiebreak is ever implemented, the study succeeds in doing something important: it challenges a long-held assumption that winning more sets always means being the better player. In most cases, that assumption holds. In a small but significant number, it does not.

Research paper: Making Tennis Fairer: The Grand Tiebreak – Journal of Sports Analytics
https://doi.org/10.1177/2215021825138875