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Tommy Robredo stunned the great Roger Federer in straight sets Monday in fourth-round action at the U.S. Open.

Robredo, who came in winless in 10 career meetings against the Swiss legend, pulled out a 7-6 (7-3), 6-3, 6-4 victory to reach the Open quarterfinals for the first time in the his career.

"Roger for the moment is the best player of all time," Robredo said. "To beat him in a huge stadium like the U.S. Open and in a Grand Slam...it's like a dream, no?"

Rain forced a slew of changes on Day 8, and all four fourth-round matches scheduled for Monday were in progress at the same time.

Federer, seeded seventh, had not lost before the quarterfinals in 36 consecutive Grand Slam tournaments prior to a second-round loss to Sergiy Stakhovsky at Wimbledon.

The 17-time major champion couldn't start another streak as he converted just 2-of-16 break chances as opposed to a 4-of-7 success rate for the 19th-seeded Robredo, who was 0-7 in fourth-round matches at the Open.

"I missed so many opportunities," said Federer, who suffered his earliest exit at this tournament since a round-of-16 dismissal in 2003. "Tommy did a good job to keep the ball in play and make it difficult for me today."

Federer's loss denied fans a shot at a showdown against Rafael Nadal. The two superstars had never squared off at the U.S. Open.

The second-seeded Nadal lost the first set to 22nd-seeded Philipp Kohlschreiber on Monday before quickly recovering and rolling to a 6-7 (4-7), 6-4, 6-3, 6-1 victory.

Nadal, the 2010 U.S. Open champion and 2011 runner-up, is a perfect 19-0 on hardcourts this year and has never lost in six career meetings with fellow Spaniard Robredo.

Fourth-seeded David Ferrer, also from Spain and a semifinalist in Flushing last year, fended off 18th-seeded Janko Tipsarevic, 7-6 (7-2), 3-6, 7-5, 7-6 (7-3).

Next up for Ferrer is eighth-seeded Richard Gasquet, who outlasted Milos Raonic, 6-7 (4-7), 7-6 (7-4), 2-6, 7-6 (11-9), 7-5 in a match that lasted four hours, 40 minutes.

The Frenchman saved a match point in the fourth set tiebreaker, broke the Canadian's serve at love to go up 6-5 in the fifth, and served out the match to end the marathon on Court 17.