PARIS - Can one match really change everything?
Roger Federer certainly hopes so. Rafael Nadal certainly thinks not.
Can one win over Nadal - in a final on clay last weekend - reverse Federer's recent malaise? Perhaps even point him toward a title at the French Open, the only Grand Slam tournament he hasn't won?
Can one loss to Federer - in straight sets in Spain - chip away at Nadal's sense of superiority? Perhaps even portend an end to his unbeaten run at Roland Garros, where he will try to win a record fifth consecutive championship and take the second step toward a true Grand Slam?
This much is indisputable: Federer's victory over Nadal at the Madrid Open simultaneously gave the Swiss star his first tournament title in more than six months and ended the Spaniard's 33-match winning streak on clay. Those facts alone at least change the conversation heading into the French Open, which starts Sunday.
''I am very excited about going to Paris, whereas a couple of weeks ago, I was still a little bit unsure about my game,'' Federer said, ''and not sure if I could win the French.''
Nadal, for his part, graciously noted after that setback, ''He was better. That's all there is to it.'' Less graciously, Nadal also pointed out that the altitude and other particulars of the Madrid tournament favoured Federer.
Yet we have seen this before: Two years ago - also in a final, also on clay, also shortly before the French Open - Federer beat Nadal at Hamburg, Germany, to end Nadal's 81-match winning streak on the red surface, then spoke boldly about ''dictating play.''
Some thought that would foreshadow a title for Federer in Paris. But he lost to Nadal in four sets in the 2007 French Open final, the same way the 2006 French Open ended. In 2008, Nadal beat Federer in three sets in the final. In 2005, Nadal beat him in the semifinals.
''The toughest opponent on this surface is Nadal. There's no question about it. But, still, Roger has been playing really well on this surface,'' said fourth-ranked Novak Djokovic, twice a French Open semifinalist.
There are, of course, other story lines that merit attention over the 15 days of the year's second major tennis tournament:
-The Williams sisters try to make up for their 2008 French Open, when both lost to unheralded players in the third round. Serena Williams aims for her third Grand Slam trophy in a row, even though she has a balky knee and a four-match losing streak.
-Maria Sharapova recently played her first singles match in nearly 10 months after having surgery on her right shoulder last year.
-Dinara Safina wants to back up her No. 1 ranking with her first major championship. Ana Ivanovic has struggled since winning her only major title at Roland Garros last year.
-New men's No. 3 Andy Murray and Djokovic plan to show that the gap from Nadal and Federer to them is narrowing, while talented players such as No. 5 Juan Martin del Potro and No. 7 Gilles Simon want to turn promise into results on the big stage. Newlywed Andy Roddick, meanwhile, would like to win a French Open match for the first time since 2005.
And yet, if the recent past is any indication, this tournament will come down to Nadal and Federer.
Nadal, thanks in part to victories over Federer in five-set finals at Wimbledon and the Australian Open, has the No. 1 seeding in Paris for the first time. After all those years atop the rankings, Federer is No. 2.
With 13 Grand Slam singles titles, Federer needs one to tie Pete Sampras' record. With six, Nadal is gaining. Federer bids again to become the sixth man with a career Grand Slam, while Nadal's victory in Australia means he can eye the first calendar-year Grand Slam by a man since Rod Laver's in 1969.
''He definitely has a chance,'' Federer said.