LONDON - Roger Federer rated his masterful 6-3, 6-0 demolition of Rafael Nadal at the ATP World Tour Finals as one of the best performances of his life.

Federer has enjoyed many remarkable days during his illustrious career, but even the 16-time Grand Slam champion was surprised by how completely he overwhelmed his longtime rival at London's O2 Arena on Tuesday.

The 30-year-old took just an hour to crush Nadal with the kind of imperious display that ranks alongside the very best Federer has ever produced.

Even when Federer had beaten Nadal in the past, he has usually been pushed to the limits in the process.

Nadal may have been slightly affected by the illness and injury that has dogged him in recent weeks, but Federer had never beaten the Spaniard by such an emphatic margin before, and the dominant manner of the victory made it one of his all-time great performances.

"It's definitely one of the nice ones, that's clear. I had some good ones in my lifetime, but this one ranks high because it's against my biggest rival," Federer said.

"It's the World Tour Finals, where it really matters. That I've been able to come through so convincing is a bit of a surprise to me, but it ranks extremely high.

"Possibly he struggled more early on indoors in only the second match back from five weeks out.

"But to come through so convincingly is great for me because we know Rafa has a certain standard which he does not go below.

"That's where this victory, still for me, I can rate this extremely high."

Federer's struggles against Nadal have been well documented and he went into the Group B encounter on the back of three successive defeats against the Spaniard.

But 12 of Nadal's 17 wins against Federer have come on his favored clay and the Swiss star has always fancied his chances more on the quicker hard courts.

Nadal vows to bouce back

Nadal, however, insists he can recover from his brutal defeat.

The Spaniard was powerless to prevent Federer from delivering one of his all-time great performances, but he can still qualify for the last four with a victory over France's Jo-Wilfried Tsonga in his final Group B match on Thursday.

"Now is not the moment to be down and say goodbye, it is the moment to keep fighting," Nadal said. "I'm still in the tournament and I will be in the semifinals if I win the next match.

"I didn't play badly in the first set, so I must keep a positive attitude and just accept that he played better than me."

Nadal admitted it was impossible to live with Federer in that kind of form on one of his favorite surfaces.

"I accept he played at a fantastic level. A very, very top level. Something that only one player like Roger can arrive at," Nadal said.

"When you play against Federer and he's playing like this, the only way to stay in the match is to get free points with the serve and I couldn't do that.

"He was too good for me. When I beat him in the Roland Garros final in 2008 it was a similar thing, but the difference is that was the final of a Grand Slam and this was a round-robin match.

"But his level is probably higher here because all the conditions are perfect for him as the bounce is not too high and there is no wind.

"In these conditions he can attack better than on other surfaces. But if he plays like this on the other surfaces he will still beat me. That is true."

The world No 2 has been struggling with a shoulder injury of late and also felt ill during his victory over Mardy Fish on Sunday.

And while he wouldn't blame the defeat on those problems, he did admit he had been unable to practice on Monday due to the shoulder injury.

"I woke up with the shoulder problem so I had to work to recover from that and I didn't get a chance to practice," he said.

"I didn't know if I would be able to play today but it didn't affect my match because I felt perfect.

"It won't be the last time I lose a match like this. I will try my best to play against him another time in this tournament."

Agence France-Presse