London :Roger Federer said injuries to his back and right leg played a key role in his stunning Wimbledon quarter-final defeat by Tomas Berdych on Wednesday.
Federer's reign as Wimbledon champion was brought to a sensational end on Centre Centre as Czech 12th seed Berdych ensured the world number two would miss the Wimbledon final for the first time since 2002.
After seven years of almost uninterrupted success at the All England Club, Federer was unable to subdue the big-serving Berdych as he suffered his second successive Grand Slam quarter-final defeat.
It is worry trend for the six-time Wimbledon champion, but he puts his recent struggles down to the difficulties of dealing with two injuries at once.
"I am struggling with a little bit of a back and a leg issue," Federer said. "That just doesn't quite allow me to play the way I would like to play. So it's frustrating, to say the least.
"The leg injury came in the finals of Halle. That never really went away and the back's been feeling really badly stiff for the last five or six days.
"When you're hurting, it's just a combination of many things. You just don't feel as comfortable.
"You can't concentrate on each and every point because you do feel the pain sometimes. And then you tend to play differently than the way you want to play.
"Under the circumstances I think I played a decent match. But I've been feeling bad for the last two, three matches now. It's just not good and healthy to play under these kind of conditions.
"So if there's anything good about this it's I'm gonna get some rest, that's for sure."
Federer had won eight of his previous 10 meetings with Berdych, but he found it impossible to get to grips with his opponent's ferocious serve and precise, powerful ground-strokes.
The Swiss star never looked comfortable as Berdych went for broke on every point and he insisted the defeat was more a result of the Czech's excellent display than any failings in his own game.
"I don't think I played poorly but he went after it. I know Berdych. I think I've played him 10 times already before and that's the way he plays," Federer said.
"He's been able to play more consistent for the last year or so, and I was just not able to defend well enough and I didn't come up with the good stuff when I had to. So it was disappointing.
"I had my chances. I don't think I needed to change much. The way I returned, I could have won.
"But I was just not playing well enough. And when he had to, he was able to come up with some good stuff."
By his own high standards 2010 has been a forgettable year for Federer, who has now failed to win any of his eight tournaments since beating Andy Murray in the Australian Open final in January.
But, while Federer concedes he has been below his best in recent months, he has no intention of panicking and expects to return fit and revitalised in time for the American hard court season.
"Obviously people think (going out in the) quarters is shocking, but people would die to play in the quarter-final of a Grand Slam," he said.
"It's not something I'm used to doing, losing in quarter-finals, because it's not something I've done in the last six years.
"Obviously I'm unhappy with the way I'm playing. I'm definitely struggling at the moment.
"But I'm looking forward to a rest, and then attack again in North America."