Rafael Nadal is undefeated in 19 matches on hard courts this year after coming back to beat 22nd-seeded Philipp Kohlschreiber of Germany 6-7 (4), 6-4, 6-3, 6-1 and return to the U.S. Open quarterfinals.
He will not, however, play Roger Federer next.
The second-seeded Nadal, who counts the 2010 U.S. Open among his 12 Grand Slam titles, beat Kohlschreiber on Monday night in the fourth round.
Their match ended about 21/2 hours after Federer was upset in straight sets by 19th-seeded Tommy Robredo, Nadal's quarterfinal opponent. Had Federer won, he and Nadal would have played each other for the 32nd time - and first at Flushing Meadows.
Against Kohlschreiber, Nadal faced only one break point, and saved it. Nadal has yet to lose a service game in the tournament.