World number one Roger Federer was knocked out of the U.S. Open by an inspired Tomas Berdych in the quarterfinals at Flushing Meadows.

Federer was seen as the man to beat in New York, after winning Wimbledon and regaining the world number one ranking. However, Berdych had other plans, quickly going into a two-set lead. While Federer tried to bounce back into the match, taking the third set, Berdych put in a brilliant fourth set to clinch the match 7-6 (1), 6-4, 3-6, 6-3.

Federer had nearly as many unforced errors (40) as winners (44), with Berdych doubling the ace count against his opponent.

"I just didn't come up with the goods tonight," Federer said. "It was unfortunate.

"When you end up losing at the end, you know, you always hope that you made every chance you had. He probably created more than I did, and that's why he ended up winning tonight."

Berdych will now face Andy Murray in the semi-finals, after the Olympic champion came back from a slow start to get past Marin Cilic 3-6, 7-6 (4), 6-2, 6-0.

Down a set and two breaks at one point, Murray found himself rejuvenated after the supporters shifted to the Louis Armstrong stadium late in the second set, to fight back from the brink and book himself a place in the semis.

"It definitely got much, much louder and felt more like the quarterfinals of a Slam," Murray said. "That's not a reason to get off to a bad start, though.

"You have to be able to create your own atmosphere when you're on the court. But I did play better when the crowd filled up."

Earlier, Novak Djokovic eased through to the quarterfinals after his opponent Stanislas Wawrinka retired, with Djokovic leading 6-4, 6-1, 3-1, in the fourth round match, which was postponed from Tuesday due to rain. "It's an unfortunate situation that happened with him, but I felt that I was hitting the ball well in the last two sets before that happened," Djokovic said. "Hopefully I can keep that going for the next match."

Djokovic faces Juan Martin Del Potro in the last-eight after the Argentine got the better of Andy Roddick.

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