PARIS - There was a time when a Grand Slam final between Roger Federer and Rafael Nadal was a regular occurrence.

Over a 12-major span from the 2006 French Open to the 2009 Australian Open, seven title matches were Roger vs. Rafa. No other pair of men in tennis history participated in a total of more than six Slam finals together.

"A lot of important matches for our careers," Nadal said. "A lot of emotions in these kind of matches."

And then, suddenly, it stopped. Federer and Nadal will renew their sublime rivalry Sunday at the French Open, the first time in more than two years they'll decide a Grand Slam championship.

"It's very special to have these guys back in another final," said U.S. Davis Cup captain Jim Courier, who won the 1991 and 1992 French Opens and will be on hand Sunday to present the trophy to the winner. "You never know if you're going to get another one. Just when you think you're in the sweet spot of an era, it can change very quickly."

Another change for the French Open occurred at Court Philippe Chatrier, when a fan yelled in Mandarin while China's Li Na tossed the ball while serving at match point in the women's championship.

After so many years of "Come on" and "Allez" and "Vamos," there's a new language on the tennis landscape.

Li became the first Chinese player, man or woman, to win a Grand Slam singles title by beating defending champion Francesca Schiavone of Italy, 6-4, 7-6 (0), at Roland Garros on Saturday. The sixth-seeded Li used powerful groundstrokes to compile a 31-12 edge in winners, and won the last nine points of the match, a run that began when the fifth-seeded Schiavone was flustered by a line call she was sure was wrong.

At her news conference, Li wore a new T-shirt with Chinese characters that mean "Sport changes everything."

As usual when it comes to Federer and Nadal, there is plenty at stake.

The top-seeded Nadal is 44-1 at Roland Garros and bidding for his sixth French Open championship, which would tie Bjorn Borg's record. Only two days after turning 25, he'll be going for a 10th major title overall. Plus, he needs a victory to prevent Novak Djokovic from replacing him at No. 1 in the ATP ranking.

The third-seeded Federer, meanwhile, seeks to add to his record of 16 Grand Slam trophies, including the 2009 French Open. He could become only the third man to own at least two titles from each of the sport's most important tournaments (he's won six at Wimbledon, five at the U.S. Open, four at the Australian Open).

And then there's this intriguing tidbit: Federer never has beaten Nadal at Roland Garros, going 0-4 - in the 2005 semifinals, and the 2006, 2007, and 2008 finals.

The only time Federer managed to win the French Open, he didn't have to face Nadal. Instead, Federer's straight-set victory in the 2009 final came against Robin Soderling, who stunned Nadal in the fourth round that year (and also happened to knock out Federer in the 2010 quarterfinals).

"It always seems to me that Rafa needs to be in a French Open final to make it special," Federer said after ending Djokovic's 43-match winning streak in the semifinals, "and I got the match I guess I was hoping for."

That's a fascinating statement, considering that Nadal is a player who troubles Federer in ways that no one else ever has. Nadal is 16-8 against Federer overall, including 5-2 in Grand Slam finals. Nadal won their most recent match, on clay last month.

"It will be one for the ages," Andre Agassi predicted. "Any time you see these two, Nadal and Federer, it's one of the most memorable moments."