Handicapping Men’s Tennis: Three Sets vs. Five
The Grand Slam tennis tournaments are a unique stage for tennis players, for several different reasons. Of course, they’re the only tournaments that consistently draw all of the world’s top players, and have the most prestige and prize money of any events on tour. But when it comes to men’s tennis, there’s another difference: the matches are best-of-five sets, rather than best-of-three.
Surprisingly, many gamblers do not give this change enough weight when handicapping tennis matches. Even among those who do take the longer matches into account, many only use it to put a greater emphasis on player conditioning and endurance. We don’t mean to say you shouldn’t do this; obviously, stamina is at a premium when you might have to play five sets several times in the same week!
However, there is a more fundamental adjustment you must make when handicapping five set matches: the favorite is more likely to win than in a standard three set match. The reason for this is fairly obvious; the longer two competitors play against each other, the better the chances are that the results will be due to the abilities of the two players, rather than any short term luck or variance.
Author King Yao explored this topic well in an article for the TwoPlusTwo Magazine. To use his example, if a player has a 60% chance of winning any one set against another player, they will have a 64.8% chance to win a three-set match against that opponent. However, they would have a 68.3% chance of winning a five-set match. Similarly, a player with a 70% chance of winning an individual set will win a three-set match 78.4% of the time, but will win a five-set match 83.8% of the time.
This is just a mathematical explanation, and we can’t just assume that the odds of every set between two players are exactly the same. But the fact is that higher-ranked men do win more often in matches at Grand Slam tournaments than in three-set matches, as we would expect based on the theoretical math we mentioned earlier. In fact, according to the data cited by Yao, higher-ranked players show an even bigger increase in their winning percentages then we’d expect based simply on the math! This is likely due to top players saving their best efforts for major tournaments, among other factors.
All of this is interesting, but how can you use it when betting on tennis? First, some bad news: it seems as though the bookmakers do realize that this effect exists, and price favorites in Grand Slam events accordingly. However, Yao found that the bookmakers do not seem to adjust the odds sufficiently to fully account for the difference in win rates among strong players. It appears that they generally adjust their lines in a way that matches the “theoretical” approach we mentioned earlier; as we said, this is smaller than the difference shown in real results.
What does this all mean to you? Given that favorites win more often than bookmakers give them credit for, it makes sense to look at favorites in Grand Slam tournaments more closely. You might often find good value there, even on favorites that have been priced very short. However, this doesn’t mean you should blindly start picking favorites at random; you’ll still want to do all the research you normally go through, handicapping each match based on all of the important factors we talk about so often on this site. Just remember to give the favorite a little extra credit – it could be the difference between a bet that’s not good enough to beat the vig, and one that’s a must play.