Djokovic-Nadal XXXVII: The (Actual) Keys to the Match

Both Rafael Nadal and Novak Djokovic have had easy routes to the US Open final.  Neither was tested before the semifinals, and neither has yet to play a top-eight opponent.  Yet both were pushed further than expected in their last matches.  Djokovic nearly lost in another tough five-setter against Stanislas Wawrinka, and Nadal looked almost human at times, spraying errors in his match with Richard Gasquet.

For all that, the field is down to the final two.  They’ve played 36 times before, with Nadal leading the career matchup 21-15. On hard courts, it is the 18th meeting, with Djokovic leading 11-6.  It is their eleventh encounter in a Grand Slam, of which Rafa has won seven of the previous ten, while they’ve split their two previous US Open finals.

Based on the most relevant pieces of this head-to-head–the last seven Djokovic-Nadal matches on hard courts, dating back to the 2010 US Open–we can identify some clear trends that tell us what to watch for, and what each player must do to seal the US Open title.

The key: Rafa’s service games

Of these last seven hard-court matches, Nadal has won three and Djokovic has won four.  If we could find some statistical indicators that each player reached when they won and failed to accomplish when they lost, we might be on to something.  Think of it like IBM’s Keys to the Match, but with actual predictive value.

Sure enough, there are plenty of indicators that fit the bill, and they almost all center on Nadal’s serve:

• In four of the matches, Nadal has served fewer than 5% aces.  In the other three, at least 7% aces.  He lost all four of the former, and won all three of the latter.
• In four of the matches, Nadal won fewer than 70% of his first-serve points.  In the other three, he won at least 71%.  He lost all four of the former, and won all three of the latter.
• In three of the matches, Nadal won fewer than 47% of his second-serve points.  In the other four, won at least 56%.  He lost all of the former, and won all but one (the 2011 Indian Wells final) of the latter.

We can sum up the importance of Nadal’s service games from a more Djokovic-centered perspective:

• In three of the matches, Djokovic won no more than 33% of return points.  In the other four, he won at least 37% of return points.  Care to guess which matches he won?

Djokovic’s service non-indicators

The numbers are not nearly so clear for Djokovic’s service games.  In the two meetings when Novak hit the most aces, Rafa won.  In three of the only four matches when Djokovic made 62% or more of his first serves, Rafa won.  (These are starting to sound like some of the more inane of the IBM keys.)

Generally, winning 65% of first serves is good enough for Novak to beat Nadal, except for last month’s match in Canada, when he won 71% of first serves and lost in a third-set tiebreak.  In Djokovic’s worst second-serve performance of the seven matches, the 2011 US Open final, he barely won 44% of those points, yet won the match.

Of course, this doesn’t mean that Djokovic’s service stats don’t matter.  It’s no accident that Novak’s first-serve percentages were much higher in the three sets he won against Wawrinka than in the two sets he lost.  On the contrary, Djokovic’s serve just isn’t as potentially dominant as Nadal’s is.

For example, in Saturday’s semifinals, Nadal won 36% of his service points on or before his second shot, while Djokovic won only 24% of his service points that way.  Nadal’s number isn’t staggeringly high (for example, both Kevin Anderson and Marcos Baghdatis topped 40% in that category in their second-round match) but it’s a number he can earn only when serving well.  When he isn’t earning those cheap, quick points against Djokovic, Novak takes away the server’s advantage, threatening to break in almost every service game.

By contrast, Djokovic–like Victoria Azarenka–doesn’t consistently earn that type of advantage on serve.  Sure, he gets some free points that way, but in general, he takes the slight advantage that serving confers and uses that as an edge in a longer rally.  In the semifinal against Wawrinka, his average service point–including aces and unreturnables–lasted more than five shots.

Getting one number for Novak

Individually, Djokovic’s service stats don’t tell us much.  But if we consolidate them into one number–Nadal’s return points won–we get a little better clue of what beating Novak requires.  In the three matches where Nadal failed to win 34% of return points, he lost.  In the two matches where he won at least 42% of return points, he won.

But if you’re counting, you’ve surely noted that I left out two matches.  In Montreal last month, Nadal won only 34.7% of return points, and won.  In the 2011 US Open final, he won 41.7% of return points, yet lost.  Djokovic can be so effective in his own return games–or simply unbeatable when given break point opportunities, like he was that day–that even a masterful return performance like Nadal displayed in that final isn’t always good enough.

So Novak’s numbers just aren’t as indicative as his opponent’s.  Instead, keep your eyes on Rafa’s serve statistics.  Despite the many long, gut-busting rallies we can expect this afternoon, Nadal has this match–like his previous hard-court meetings with the world #1–on his own racquet.