Who wins the deciding set in men's tennis?

When a men's tennis match goes to a 3rd or 5th deciding set, who is more likely to win? What can the opening sets or games of a match tell us when it comes to the deciding set? Andrew digs into 10 years worth of men's tennis stats to help us pick a winner when a match goes to a deciding set.

The most memorable tennis matches are always those epic 5 set marathons. Those matches where the afternoon shadow draws longer across the court as each game passes with neither player giving up an easy point. Or where the crowd stays gripped on the edge of their seat as the match heads into the early hours of the morning.

But when a match goes to a deciding set, is there anything that the opening sets of the match can tell us? Is there anything we can gather from the first 4 sets of a 5 set match that could help us pick a winner while betting in-play on a Grand Slame matchup? And can the first two sets of 3 set tournament match give us any indication of what might take place in the 3rd and deciding set?

I decided to take a look at 10 years worth of matches in men's tennis, dating back to the beginning of 2002, to find out.

Which set means most?

Let's first look at 5 set matches. And in particular, let's look at the winning percentages for players depending upon which sets they have won in the lead up to the 5th set decider.

Here we can see that there is something to be said for momentum, as the player that wins the 4th set goes on to win the match outright almost 55% of the time. Meanwhile, the player that wins the opening set in a match that extends to 5 sets, only goes on to to win that deciding set, just over 46% of the time.

Set win combinations

So let's then break it down a little further. Here we will be looking at which set combinations have been most successful in the lead up to a 5th set decider.

Here we can see, as we may have expected from our previous analysis, that winning the 4th set is critical to taking momentum into the 5th set.

The most successful combination has been where players not only win the 4th set, but also the 2nd set. When this occurs, the player goes on to win the final set just over 57% of the time, meaning that the player who wins the 1st and 3rd set, only wins the 5th and deciding set, just under 43% of the time.

The second most successful combination was for players who won the 3rd and 4th sets. These players went on to win the final set over 55% of the time, meaning that players who won the 1st and 2nd sets, only win the deciding set around 45% of the time.

And lastly, players who won the 1st and 4th sets, go on to win the deciding set just over 51% of the time, meaning players that won the middle 2nd and 3rd sets, in a match that extends to 5, go on to win in just under 49% of such matches.

4th Set Margins

Now let's take a look at the key 4th set and in particular, the winning percentages dependant upon the margin of victory in this key set of the match.

We can see that players who demolish their opponents in the 4th set by a clean 6-0 margin, go on to win the match just under 71% of the time, with a similar result when winning by 5 games in the 4th, going on to win almost 68% of the time.

Players who won the 4th set by 4 games to extend to a 5th set, went on to win that 5th set just under 60% of the time.

In tighter encounters, players who won the 4th by 3 games went on to win the match just under 54% of the time, while players who won the 4th by 2 games, went on to win just over 52% of the time.

Interestingly, players who managed to win the 4th in a tiebreaker by the single game margin, went on to win the 5th set just under 49% of the time.

1st Set Margins in Best of 3

Now let's take a look at matches that were best of 3 set encounters. Firstly, we will take a look at what 1st set margins might tell us when it comes to the 3rd and deciding set.

We can see that the only 1st set margin that trends towards a winning result in a 3rd and deciding set was the clean 6 game margin. Players who won the opening set 6-0 in a match that extended to 3 sets, won that 3rd set over 56% of the time.

Meanwhile players who won the opening set in a tiebreaker in such matches, went on to win the 3rd set under 45% of the time.

Overall, players who won the 1st set in a match that extended to 3 sets, won that 3rd and deciding set just under 47% of the time.

2nd Set Margins in Best of 3

Finally, let's look at 2nd set margins in best of 3 set encounters, and what they may tell us about what we can expect in 3rd and deciding sets.

Overall, players who won the 2nd set went on to win the 3rd set, just over 53% of the time, again suggesting something of the true value of momentum.

Further, players who win the 2nd set 6-0, go on to win the final and deciding 3rd set in just over 60% of such matches, while players who won the 2nd set by a margin of 5 games, went on to win the 3rd set over 57% of the time.

Players who won the 2nd set by a margin of 4, 3 or 2 games, went on to win the final set around 53% of the time in such matches, while players who won the 2nd set by a single game margin, went on to win the 3rd deciding set just under 51% of the time.

So what did we learn?

Let's conclude this analysis by listing the key points:

  • Momentum means a lot as winners of both the 4th set in Best of 5 set matches and the 2nd set in Best of 3 set matches, go on to win at a higher rate.
  • Margin of victory in the 4th and 2nd sets suggests much in terms of the likelihood of victory in the deciding set.