Roger Federer disappointed with US Open defeat

Swiss tennis player Roger Federer has admitted that it was "frustrating" to lose to Tommy Robredo in the fourth round of the US Open.

The 32-year-old suffered a straight-sets defeat to the 31-year-old Spaniard, going down 7-6(3) 6-3 6-4 on Monday.

"I've definitely got to go back to work and come back stronger, get rid of this loss now as quick as I can, forget about it, because that's not how I want to play from here on," BBC Sport quotes him as saying.

"I want to play better. I know I can. I showed it the last few weeks, that there is that level, so today was pretty frustrating."

This is the second time in a row that Federer has failed to progress to the quarter-finals of a Grand Slam.