Swiss beaten by 19th-seeded Tommy Robredo in straight sets as he fails to qualify for a 2013 grand slam final.
US Open: Roger Federer vigilant after another early loss
After crashing out in the fourth round of the US Open against an opponent who had never before beaten him, the 17-time grand slam winner Roger Federer shrugged off any notion he might quit the sport.
"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," Federer said late Monday.
"I want to play better. I know I can."
Federer fell to the 19th seed Tommy Robredo 7-6, 6-3, 6-4, dooming hopes for a potential quarter-final match with the 12-time major winner Rafael Nadal, in what would have been their first meeting on the New York hard courts.
"The story of my life: when I lose, people are shell-shocked to see me play this way. If I win, it's the best thing," said Federer, 32. "I can see that. But there's no doubt about it, I'm trying hard out there trying to make it work.
"Sometimes it just doesn't happen."
That shattered aura of invincibility gives opponents like Robredo, who says that "Roger for the moment is the best player of all time", the idea they can defeat Federer now.
"Roger, when he was No 1, compared to the Roger right now, he's not maybe with the same confidence," said the Spaniard, who had lost his nine previous encounters against the Swiss.
"Obviously, he's the same player and he plays unbelievable, but I knew that if I had a few more chances, maybe he will have a little bit of doubt."
Federer had made 36 consecutive grand slam quarter-final appearances before being upset by Ukraine's Sergiy Stakhovsky in the second round at Wimbledon, this year, having not departed a major before the last eight since the 2004 French Open.
This was the first year since 2002 that Federer did not make a major final and the first year since 2003 that he failed to reach the last eight at the US Open.
"It has been a difficult last three months," he said.
"My consistency is just not quite there yet. Maybe on a daily basis, a set-by-set or point-by-point basis, maybe that's something that has been difficult for me, so maybe that was one of the reasons I lost."
Federer takes some confidence from his lone title of the year, at Halle in June, and runs to the Hamburg semi-finals and Cincinnati quarter-finals.
"I showed it the last few weeks, that there is that higher level, so today was pretty frustrating," Federer said.
"Important for me, first and foremost, is that I move better, that I play better. My problem is in training, not actually playing matches right now."
The five-time US Open champion has no plans on making major changes to his training regimen or match strategy. He said searching for ways to make his game better promised to be an enticing challenge.
"I haven't thought of it right away," he said. "Nothing goes past the hard work. I'll make sure I'll put the work in. Once I decide what that is, I'll believe in it and go after it.
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