11-23. That's the damning stat that stares at Roger Federer as he prepares for the ultimate battle in his tennis career. No opponent has bothered him like Rafael Nadal has: Federer admitted in the lead-up to the final that the clay battles had left a scar -- Nadal is up 13-2 on clay and 5-0 at Roland Garros -- and affected the way he approached some of their earlier clashes on other surfaces as well.
Federer has done better when not playing on clay (it's 10-9 to Nadal on other surfaces), but the numbers don't look good for him whichever way you look at it. In all Grand Slam matches, Nadal is up 9-2, and at the Rod Laver Arena, he has won all three of their meetings in progressively fewer sets -- five in 2009, four in 2012, three in 2014. In the post-match interview after the semi-final, Federer tried to put a positive spin on recent results by pointing to the win in Basel, but that was indoors, the only conditions where Federer is convincingly ahead (5-1).
The overall numbers are common knowledge, but there's also the narrative within matches that has increasingly been going against Federer in the last few years.
Through most of their rivalry, the story of many of their close matches has been Federer's inability to win the big points, and Nadal's greater composure and grit at the clutch moments. The break-point numbers tell that tale most eloquently: in the first 26 matches between the two players, with the head-to-head 17-9 at the time, Nadal only had two more break opportunities than Federer -- 230 to 228. The difference was the number of times Nadal converted those chances -- 101 times, compared to Federer's 83.
In several key matches, Nadal's ability to stave off break points was the most important stat: in the 2007 French Open final, Federer converted one out of 17; in the epic 2008 Wimbledon battle, it was one out of 13; at the Australian Open the following year he managed six of 19, and in the 2011 French Open final he had five out of 15. In each of those matches, Nadal did far better on break points to ultimately win. The difference was especially stark in the Grand Slams, where Nadal played the big moments much better; in other tournaments there was little to choose between the two.
More recently though, that narrative has changed quite significantly. In eight matches between them since the start of 2012, the issue for Federer has no longer been about grabbing his chances; it has been about not creating enough of them in the first place. In these eight matches, starting with the 2012 Australian Open semi-final, Federer has created only 35 break opportunities while Nadal has had almost twice as many at 67.
In four of their last six matches, Nadal has allowed Federer only two break opportunities. Worryingly for Federer, three of these were on hard courts, including the 2014 Australian Open semi-final. The percentage of return points won for Federer has dropped from 36.97% in the earlier period to 32.09%, while Nadal's has increased marginally from 37.28% to 39.26%. From creating a break chance once every 1.5 return games on average, Federer is only creating one every three games, while Nadal's average continues to remain at around 1.5. In short, Federer has handled Nadal's serve far poorer than he used to in his pomp.
Overall, the gap between the two in their head-to-head match-up has increased in the recent past, in Nadal's favour: in their first 26 matches, Nadal had only won 56 more points than Federer, an average of two points per match. In their last eight matches, he has won 76 more points than Federer, an average of almost 10 extra points per encounter.
The good news for Federer, despite all these unfavourable numbers, is that the two have hardly played each other in the last couple of years, and Federer has tried to get more aggressive and shorten points over that period. And in this tournament itself, Federer has been smart with break-point conversions, achieving the break 31 out of 64 times, compared to Nadal's 27 out of 77.
However, comparing their numbers against other players is almost always irrelevant when these two take on each other. In a sport where individual match-ups matter so much, Nadal ticks all the boxes, and despite Nadal's exertions from an epic against Grigor Dimitrov on Friday, and despite an extra day's rest for Federer, it is impossible to not have Nadal as the favourite going into Sunday's clash.
And while we are on numbers, here is another to chew on: Nadal has won each of their last six meetings in Grand Slams, twice in Paris, three times in Australia and once at Wimbledon. Going by all these numbers, it is likelier that Nadal's Grand Slam tally will go up to 15, than Federer climbing to 18. Unless Federer can combine the break opportunities of the first 26 matches with the conversion rate of the last eight.
S Rajesh is ESPNcricinfo's stats editor