John Isner held off Dudi Sela to advance to the quarterfinals of the Delray Beach Open.

Delray Beach, Florida – John Isner held off Dudi Sela to advance to the quarterfinals of the Delray Beach Open after No. 3 seed Kei Nishikori exited the tournament because of a hip injury.

The second-seeded Isner squandered four match points in the third set after leading 4-1, but the towering American recovered from a 5-2 deficit to prevail in the tiebreaker for a 3-6, 6-1, 7-6 (5) victory that earned him a spot in the quarterfinals for the third consecutive year.

“More times than not, when I'm up 4-1, I close it out,” said Isner, who is playing his first tournament since exiting the Australian Open with an ankle injury last month. “It definitely didn't need to go to 5-5 when I was up 4-1. I put a lot of stress on myself when I do that.”

The world No. 13 will face American compatriot Rhyne Williams on Friday. The qualifier ousted wild-card Marcos Baghdatis 6-7 (7), 6-4, 6-2 to reach his second ATP quarterfinal.

Nishikori's bid to win his second consecutive ATP title came to an abrupt halt when the top-ranked Asian was forced to retire during the first set of his second-round match because of a left hip flexor injury.

Nishikori was trailing Teymuraz Gabashvili of Russia 4-2 when he retired. He said he experienced discomfort for the first time during his first-round win Tuesday.

“I tried to play, but if you're not 100 percent, it's tough,” said Nishikori, who is ranked No. 15 in the world and was coming off a win in Memphis last week. “I couldn't do anything today. It's going to take some time to recover. It's shocking this happened, especially since I've been playing well.”

Gabashvili advanced to the quarterfinals on Friday and will face No. 7 seed Marin Cilic of Croatia, who defeated American wild-card Ryan Harrison 6-3, 6-4. – Sapa-AP