WIMBLEDON, England — The outside courts were bustling at Wimbledon on Saturday with rank-and-file players pairing off to practice with the grass quiet beneath their sprinting, shuffling feet. But courtside, as the coaches, agents and commentators looked on in the June gloom, the chatter quickly turned to the favorite for the men's title.

For the last four years, little brainpower has been required to decide who deserved that honor. Roger Federer has ruled Wimbledon like Bjorn Borg and Pete Sampras before him and has now won five times in a row on the lawns of the All England Club.

But this year, for a change, there is a genuine debate under way.

Rafael Nadal overwhelmed Federer in the French Open final, taking his clay-court domination to a higher plane, and then kept right on competing. He caught a high-speed train across the English Channel the day after holding up the trophy in Paris and went on to win the prestigious grass-court tuneup at Queen's Club, beating Novak Djokovic in the final.

"Nadal was just a wrecking ball over there," Brad Gilbert, the American coach, said Saturday. "His movement was unbelievable, and he was serving so well. And his competitiveness was extraordinary.

"I watched the whole final, and it was one of the best tennis matches I've ever watched. Those guys were absolutely bone-crushing the ball."

Meanwhile, Federer was winning his own grass-court tuneup in Halle, Germany, against a weaker field. He did not lose his serve once and ran his victory streak on grass to 59 matches.

Andy Roddick, who has a 2-15 record against Federer and has never beaten him at Wimbledon, was quick to reject the notion that Federer is more vulnerable this year.

"At Queen's, I think I got the question, 'Can Roger win Wimbledon?"' Roddick said. "I found that to be one of the most ridiculous questions I've ever answered in my life. You know, he's won it five times. I'm not sure what else he has to do."

Federer's record so far in 2008 is 37-8: good but not up to the standard he set in 2005, when he lost only four times, or 2006, when he lost five times.

Roddick was runner-up to Federer in 2004 and 2005, but this year he's seeded sixth and considered a darkhorse when the tournament starts Monday. Given Nadal's improvement on grass and the emergence of Australian Open champion Novak Djokovic, Roddick faces more potential obstacles than ever at Wimbledon.

"The three guys have established themselves as most consistent on tour this year," Roddick said. "They're certainly the favorites, but I'd consider myself probably right after them."