How to Bet on Tennis

A podcast and written guide

For Wimbledon, I got the chance to talk and write about tennis for Unabated, one of the best sites for sports betting resources and general education.

Here is the Spotify link to the podcast we recorded, and here is the Youtube link.

Here is the written guide.

A couple of my favorite parts:

Why niche markets are the easiest to beat, despite the high house edge

“People should never be put off by big vig. Big vig is just fear… one thing that is uniform throughout twenty years of me and bookmaking is that the places where there is the biggest vig are the places where there’s actually still too little vig.” –– Matthew Trenhaile, former Pinnacle trader.

Bets like “will either player win their first two service games without losing a point” or “will Novak Djokovic have more or less than 14.5 double faults all tournament” are now commonplace, and increasing as sportsbooks offer new wagers to entice users to gamble at their site.  

These markets are tough to price, and even tougher to keep up to date. While most spreads and totals move directionally with the moneyline, sportsbooks don’t have a perfect formula for how to change the odds in a market they just started offering a week ago.

Imagine Novak Djokovic had four double faults in the first round, when he was expected to have just two. Should the line be adjusted up because he’s double faulting more? Or should it be adjusted down because he’s playing badly, and is likely to lose early and play fewer matches?

No one really knows. These markets don’t have an efficient price discovery process, meaning it’s often your guess against the trader or software which created the odds. That might sound daunting, especially when they get to add a big vig. But it’s easier to beat the book head-on in Tier 3 markets than it is to beat them in Tier 1 and 2 markets, where thousands of sharp bettors have acted as their consultants and hammered the line into place.  

How other bettors have beaten the books

For both men’s and women’s matches, if a set reaches 6-6 they play a tiebreaker. This counts as a game for the game total, meaning the most games a set could have is 13 (7-6).  

Historically, this was the case for all sets, except the deciding set in Grand Slams. 

There, sets had to be won by two games. There was no tiebreaker to cut them short. In the late 2010s this began to change, in response to matches like John Isner’s 2010 Wimbledon marathon against Nicolas Mahut, which ended 70-68. The match took more than 11 hours over three days to complete, and was a scheduling nightmare.  

In 2022 the Grand Slam Board announced that all four majors would conclude with a tiebreak in the final set. (Although it would be first to 10 points instead of seven). But that rule change wasn’t immediate or universal. 

In 2019 the four majors had three different scoring systems. The U.S. and Australian opens played a tiebreaker at 6-6 in the final set. Wimbledon played a tiebreaker at 12-12 in the final set. And the French Open was still win-by-two. (Leave it to the French.)

The variation was confusing to players, fans, and sometimes sportsbooks. Between 2019 and 2021, many sportsbooks either didn’t account for these differences or their models did a poor job. 

Savvy gamblers recognized this and acted accordingly when matches reached the fifth set. They bet the total games Under at the the U.S. and Australian opens. At the French Open and Wimbledon they bet the Over.

Fooled by randomness

Tennis is an individual sport. There are no team dynamics or substitutions: every point is up to a single player. This can make it easier, as a fan and bettor, to create simplistic narratives about what will happen. 

Sometimes these narratives are accurate, and lead to profitable bets. Understanding player tendencies is an important part of predicting how they’ll perform in the future. If you watch enough matches you’ll likely stumble across a bettable edge.  

More often than not, however, they’re flawed. For example, one commonly held belief among tennis fans is that a player who saves a breakpoint and holds serve is more likely to break their opponent’s serve in the next game. 

But when you look at the data, it just isn’t true. When investigating this phenomena Jeff Sackmann, founder of tennis data aggregator website Tennis Abstract, said: 

“Momentum, the basis for so many of the beliefs that make up tennis’s conventional wisdom, is surely a factor in the game, but my research has shown, over and over again, that it isn’t nearly as influential as fans and pundits tend to think. Once we hear a claim like this one, we tend to notice when events confirm it, reinforcing our mostly-baseless belief. 

When we see something that doesn’t match the belief, we’re surprised, often leading to a discussion that takes for granted the truth of the original claim. Our brains are wired to understand and tell stories, not to recognize the difference between something that happens 77 percent of the time and 79 percent of the time.”

Although Sackmann wasn’t talking about betting, his research highlights a crucial lesson for gamblers: relying on perceived patterns rather than objective data can lead to costly misconceptions. 

Check out the rest of the guide at Unabated