How Much Is the First Set Worth? Tennis Win Chances Before and After

When a first set ends, the scoreboard tells you something the pre-match price could only guess at. I wanted to know how much it tells you. By how many points does winning or losing set 1 shift a favourite's chance of winning the match, and does that depend on how short the price was? Across 92,620 priced tour-level matches, the answer is large and lopsided.

Taking the first set rather than dropping it was worth +56.3 points of match win chance to the pre-match favourite. The gain from winning it shrinks as the price shortens. The cost of losing it stays heavy until you reach the very shortest favourites. I keep this split in mind every time I check a set score for my ATP and WTA predictions page, and the four charts below show why.

Break 1Favourites' match win rates split sharply after set 1

Start with the raw outcomes. A favourite priced 50-60% before the match won 82.2% of the time after taking set 1 and only 23.8% after losing it. In the 70-80% band the figures were 91.4% and 40.8%, and the lower figure comes from 6,408 matches in which the favourite dropped the opener.

Even the heaviest favourites are exposed. Those priced 90% or more won 71.5% after losing set 1, with a 95% range of ±3.6 points from 600 matches. That is a smaller sample than the other bands, but the signal is still clear.

What I take from this is that the first set puts the favourite into a different match. In the 80-90% band, losing set 1 left them at 52.7%, close to a coin flip, when they had gone on court as heavy favourites.

Break 2Winning set 1 helps less as the price shortens

This chart measures the move against the price itself. The upward swing after winning set 1 falls steadily, from +26.8 points in the 50-60% band to +5.2 points in the 90%+ band. A short favourite was already expected to win, so confirming it adds little. The downward swing barely changes across the middle bands: −33.8 points at 60-70% and −31.8 points at 80-90%.

The damage only eases at 90%+, where it falls to −21.8 points on a priced 93.3%. For a bettor, the asymmetry is what matters. A short favourite going a set up tells you far less than the same player going a set down.

Break 3Fair match odds jump in both directions after set 1

Turning rates into odds makes the move easier to feel. A 50-60% favourite's fair price of 1.81 before the match shortened to 1.22 after winning set 1, or drifted to 4.20 after losing it. An 80-90% favourite that won the opener went on to win 94.9% of the time, which is fair odds of 1.05 and leaves almost nothing in the price.

The right-hand column is the one I watch. An underdog that won set 1 against a 70-80% favourite went on to win 59.2% of the time, fair odds 1.69. In other words, the outsider became the more likely winner.

One caveat, in my own words: these are hindsight splits. Once the set is known, the in-play price has already moved. These fair odds also carry no margin and ignore early set 2 scores, injuries and serve order. Treat them as a yardstick for judging a live quote, not as a price you can expect to find.

Break 4Best-of-five dulls the first set; surface barely matters

The gap between winning and losing set 1 was +56.8 points in men's best-of-three and +58.8 points on the WTA tour. In men's best-of-five it was only +41.8 points. Two extra sets give a favourite room to recover. By surface, the figures sit almost on top of each other: +56.6 points on clay, +54.8 points on grass and +56.3 points on hard courts.

I am a surface-first analyst, and even so this did not surprise me. Surface decides who is favourite in the first place, and the price already accounts for it. Once a set has been played, the format matters far more than the court.

Written bySophie Laurent

Tennis writer at htft.tips, based in Paris. Surface, scheduling and fatigue tell me far more than a ranking ever will.

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