NEW YORK It's a rivalry that's produced some unforgettable matches - and now it's one that is set to enter the record books.
When Rafael Nadal and Novak Djokovic square off for the U.S. Open men's title on Monday night, it will be the 37th meeting of their careers - surpassing the previous mark held by John McEnroe and Ivan Lendl for most matches played between two opponents.
Said Nadal of the looming showdown: "When you are involved in these kind of matches, you feel special."
To be sure, the No. 1 ranked Djokovic and the second-seeded Nadal have a long history.
This will be their third meeting in the past four years with the U.S. Open title on the line. Nadal won the first match in 2010 and Djokovic won the rematch in 2011. Both were grueling four-set matches.
"It's always the biggest challenge that you can have in our sport now," Djokovic said of playing Nadal. "I mean, he's the ultimate competitor out there. He's fighting for every ball and he's playing probably the best tennis that he ever played on hard courts."
The mutual respect is a reflection of how evenly matched the Serb and Spaniard have been.
"Novak is a great opponent," said Nadal after winning his semifinal on Saturday. "We already play a lot of important matches for our career, so that makes that confrontation special."
Nadal has won 21 of the 36 prior matches, but Djokovic holds an 11-6 edge on hard courts.
In addition to the split at Flushing Meadows, they've met in the final of each at the other three Grand Slams.
One of those matches became an instant classic: At the 2012 Australian Open, Djokovic grinded out a five-set win over Nadal in a match that lasted nearly six hours, setting a record for a Grand Slam final.
But Nadal would have his revenge later that year at the French Open, winning a four-set match that lasted two days because of rain.
This year has been no different. Both players are at the top of their game, having each claimed one major in 2013 (Djokovic won the Australian Open and Nadal won the French).
So who holds the edge tonight at Arthur Ashe Stadium? The hard court would seem to favor Djokovic - the Serb has the most wins on tour this year on the surface (31). However, Nadal's 2013 record on hard courts? A perfect 21-0.
Nadal, who is a year older than Djokovic, holds one major statistical advantage over his rival. The Spaniard has claimed 12 Grand Slam titles to Djokovic's six. A win for Nadal would bring him one close to Roger Federer's 17 grand slams; a win for Djokovic would tie him with John McEnroe and Mats Wilander on the all-time slam list.
Also possibly on the line is the year-end No 1 ranking. After sitting out the second half of 2012 with an injury, Nadal has been racking up points with unparalleled ferocity. Although there are still many tournaments to be played this year, conventional wisdom is that Djokovic must hold off Nadal today to improve on his own points as a finalist last year - and to keep Nadal at bay.
"Rafa is I think in a better position right now for that (year-end) ranking," Djokovic said on Saturday, adding: "I'm fighting for it. I mean, you know, I need to play well and I need to win tournaments in order to finish No. 1. I'm aware of that."
And of course there's the unofficial bragging rights. Whoever wins today will have won two of the four tennis Grand Slams in 2013. Many players say they would rather accumulate Grand Slams than have the No. 1 numerical ranking.
"Grand Slams always take the best out of every tennis player in the world, because these are the tournaments where all the attention is directed from the world of sport," said Djokovic. "These are the tournaments that are most valuable in our sport."