There’s no structural bias toward the player who serves first. If tennis players were robots, it wouldn’t matter who toed the line before the other.
But the conventional wisdom persists. Last year, I looked at the first-server advantage in very close matches, and found that depending on the scenario, the player who serves first in the final set may win more than 50% of matches–as high as 55%–but the evidence is cloudy. And that’s based on serving first at the tail end of the match. Winning the coin toss doesn’t guarantee you that position for the third or fifth set.
Logically, then, it’s hard to see how serving the first game of the match–and holding that possible slight advantage in the first set–would have much impact on the outcome of the match. There’s simply too much time, and too many events, between the first game and the pressure-packed crucial moments that decide the match.
Yet, the evidence points to a substantial first-serve advantage.
In ATP main-draw matches this year, the player who served first won 52% of the time. That edge is confirmed when we adjust for individual players.
39 players tallied at least 10 matches in which they served first and 10 in which they served second. Of those 39, 21 were more successful when serving first, against 17 who won more often when serving second. (Marcos Baghdatis didn’t show a preference.) Weigh their results by their number of matches, and the average tour-level regular was 11% more likely to win when serving first than when serving second. Converted to the same terms as the general finding, that’s 52.6% of matches in favor of the first server.
That’s not an airtight conclusion, but it is a suggestive one. One possible problem would arise if lesser players–the guys who play some ATP matches against that top 39, but not enough to show up in the 39 themselves–are more likely to choose returning first. Then, our top 39 would be winning 52.6% of matches against a lesser pool of opponents.
That doesn’t seem to be the case. I looked at the next 60 or so players, ranked by how many ATP matches they’ve played this year. That secondary group served first 51% of the time, indicating that the guys on the fringe of the tour don’t have any kind of consistent tendency when winning the coin toss.
For further confirmation, I ran the same algorithm for ATP Challenger matches this year. That returned another decent-sized set of players with at least 10 matches serving first and 10 matches serving second–38, in this case. The end result is almost identical. The Challenger regulars were 9% more likely to win when serving first, which translates to the first server winning 52.2% of the time.
This is a particularly interesting finding, because in the aggregate, these 38 Challenger regulars prefer to serve second. Of their 1110 matches so far this year, these guys served first only 503 times–about 45%. Despite such a strong preference, the match results tell the story. They are more likely to win when serving first.
When we turn our attention to the WTA tour, the results are so strong as to be head-scratching. Applying the same test to 2013 WTA matches (though lowering the minimum number of matches to eight each, to ensure a similar number of players), the 35 most active players on the WTA tour are 28% more likely to win when serving first than when serving second. In other words, when a top player is on the court, the first server wins about 56.3% of the time. 24 of the 35 players in this sample have better winning percentages when serving first than when serving second.
For something that cannot be attributed to a structural bias, a factor that can only be described as mental, I’m reluctant to put too much faith in these WTA results without further research. However, the simple fact that ATP, Challenger, and WTA results agreed in direction is encouraging. The first-server advantage may not be overwhelming, but it appears to be real.