Roger Federer has just been ousted by Tommy Robredo in the fourth round of the U.S. Open. And even more surprisingly, the Spaniard did it in straight sets, 7-6 (6), 6-3, 6-4 to beat the Swiss legend for the first time in his career.

Since 2002, Federer has made at least one Grand Slam final every year. Except in 2013 when the best he could do was a semifinal appearance at the Australian Open. Federer reached the quarterfinals at the French Open and just the second round in Wimbledon.

"It has been difficult for me in the past 3 months ... (i) can't find the consistency ...," a visibly frustrated Federer said in a postmatch interview.

Against the inspired Robredo, the 5-time U.S. Open champion hit more winners, 45-31, but had more unforced errors, 43-26. The Spaniard took advantage on break points as well and converted 4-of-7 or 57 per cent.

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Robredo lost his first ten head-to-head meetings with Federer but is now going to the U.S. Open quarterfinals awaiting the winner of the Rafael Nadal- Philipp Kohlschreiber match.