Behind 27 aces, American John Isner defeated Roger Federer on Thursday 7-6(3) 3-6 7-6(5) in the third-round of the Paris Masters. Isner needed four match points before closing out the Swiss star on a service winner.

Federer, a No. 3 seed in the tournament, clawed back from a 6-2 deficit in the third-set tiebreaker, but he simply couldn't keep pace with Isner's serve in a match that lasted two hours and 16 minutes.

Federer entered the tournament with momentum, having defeated Rafael Nadal on Sunday for his seventh Basel title. He seemed to coast through the second set and on his way to reaching the quarterfinals, but Isner's serve seemed to be too much of a challenge in the third set.

"It's tough to get out of the tournament not having lost your serve but that's how it can go against John," Federer told reporters.

This is the deepest the No. 13-seed Isner has gone at the indoor tournament since his semifinals appearance in 2011. Isner will next face David Ferrer of Spain. Ferrer has a 5-1 record over Isner.