A very brief history of Federer vs. Nadal on hard courts

Identifying The Most Important Factors when Federer plays Nadal

***Corrected and Updated version***

Nadal fans frequently argue that his strong head to head record against Federer, considered by many to be the greatest tennis player, is evidence that Rafa is instead the greatest of all time. Nadal does enjoy a substantial lead, leading 22-10. However, it should be pointed out that many of those matches occurred on clay, where Nadal is the undisputed king of clay, winning an astounding 293 matches and losing only 21 on the dirt at the ATP level. What's even more astounding is that 12 of those losses occurred while Nadal was 18 or younger. Only 3 people have ever beaten Nadal more than once on clay: Gauston Gaudio beat him three times, though all of those victories were while Nadal was 18 at the oldest; Federer has beaten him twice on clay, and Djokovic has beaten him three times. But I digress--this isn't about the greatest of all time argument or Rafa's dominance on the clay. 

In a few hours, Federer and Nadal will do battle for the 33rd time in their careers. What's more relevant here is the head to head on hard courts. Currently Nadal leads 8-6 on hard courts, though prior to Federer's lackluster 2013 season in which he lost to Nadal three times on hard courts, Federer led the head-to-head record 6-5. 

This will be their fifteenth battle on hard courts, and to try to get a sense of what matters most (note: among variables in the data that was easily available to me!) in their match-ups on hard courts. Most definitely there are some factors here that are not being accounted for. Court speed is a factor, and some hard courts are known to play faster or slower than others. 

But for now...

I calculated some very simple correlations: The larger the absolute value, the stronger the effect, or in other words, the more influence it has on the outcome of the match. These were calculated as variables influencing whether Federer wins or loses against Nadal on hard courts. These numbers considered only hard court matches--clay and grass were excluded.

Variable Corrrelation Rank 1stReturnWon 0.79 1 BP Faced/Set -0.77 2 1stserveWon 0.64 3 Aces 0.41 4 Break Chances/Set 0.42 5 2ndserveWon 0.35 6 2ndReturnWon 0.29 7

Note: 0 means zero relationship to the outcome of the match, and the closer a value is to 1, the stronger the influence on Federer's chance of winning. Negative values indicate that the variable is associated with Federer losing to Nadal. 

1. The most important factor (in this very, very simple analysis based on a very, very small sample):The percentage of point Federer wins on Nadal's first serve. If Federer has a good read on the serve and can prevent Nadal from getting easy points on the first serve and win some of those points, it will certainly improve his chances.  In his losses to Nadal, he never won more than 34%, and in half of his losses to Nadal he won less than 26% when returning first serves.  In all of Federer's victories he won at least 35% of points on Nadal's first serve.  At the risk of sounding too much like IBM's keys to the match: If Nadal is winning 65% or more on first serves, his chances are probably pretty good. If Federer's return game is on, or Nadal doesn't serve well and Fed can make a bigger dent on return games (grabbing at least 35%, but probably more like 40%), Federer's chances are better.

2. The second most important variable (for practical purposes, just as important as the first): How often Federer faces break point in a set. The more times he gets himself down a break point to Nadal, the more likely Nadal will win. Federer has to stay ahead on serve to have a good chance. Interestingly, the size of this effect is almost twice the size of the effect of how often Federer has a chance to break Nadal, so the data suggests that Federer having a strong service performance is more critical. 

In most (6 out of 8) of Nadal's wins, Federer faced at least 3 break points per set; In Federer's hard court victories he never faced more than two break points per set--the most trouble Fed has faced on serve and still managing to beat Nadal was 1.8 break points per set in the 2005 Miami final. Only in two victories did Federer face more than one break point per set. 

So Federer's going to have to stay ahead on serve and not give Nadal too many leads. Nadal is too good of a returner to be able to hold serve if he has very many chances to break, so if Federer can serve as well as he did against Tsonga in round 4 (facing only a single break point), he has a good chance at beating Nadal.

The third strongest correlation--or for our purposes, third most important variable influencing the match outcome is Federer's percentages on winning first serve points.Of course, the better he does on first serve, the better his odds of winning. Interestingly, the points on first serve seem to have a relatively larger influence on the outcome compared to the second serve. In four of six of Federer's victories over Nadal, his winning percentage on 1st serve was at least 80%, and in the other two Roger returned well and managed to break serve often. 

So I'd say for Federer to win, he needs to put up these kinds of numbers:
1. Limit the percentage of Nadal's points won on first serve to the low 60s--he should minimally win 35% of Nadal's first serves.

2. Keep break point chances to a minimum--if he can keep it to only one break point per set, he has a good chance, but if he offers Nadal two or three, or more--chances to break, Federer can probably count on dropping serve and he'll have to play very well on the return game to compensate and break back often.

3. Federer needs to either win at least 80% on first serves if he has a mediocre day returning. He can perhaps afford to win 75% if he makes up for it with a strong return performance. 

It's a tough call--many of Federer's wins over Nadal were on indoor hard courts, but Federer's numbers thus far suggest that he might be able to perform at a high enough level to beat Nadal. Perhaps it will all come down to the weather--if it rains on Melbourne and the roof is closed, the conditions may favor Federer and give him the edge.

I'm reluctant to make a prediction for this one, but I think Federer is playing well enough to beat Nadal. Nadal's performance thus far does not suggest that he unstoppable--Dimitrov very nearly had two sets on Nadal. I think if Dimitrov can push Nadal, an in-form Federer firing on all cylinders will beat Nadal playing at a level that is not his absolute best.

I'm going with Federer in 4 sets.