John Isner held off an upset bid by Dudi Sela of Israel on Thursday night to advance to the quarterfinals of the Delray Beach Open after No. 3 seed Kei Nishikori of Japan exited the tournament because of hip flexor injury.
The second-seeded Isner squandered four match points in the third set after leading 4-1, but the 6-foot-10 American rallied 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.
He will face American qualifier Rhyne Williams on Friday night. Williams ousted wild-card Marcos Baghdatis of Cypress 6-7 (7), 6-4, 6-2.
Nishikori was trailing Teymuraz Gabashvili of Russia 4-2 when he decided to stop the match because of a left hip flexor injury.
Gabashvili advanced and will play No. 7 seed Marin Cilic of Croatia, who defeated American wild-card Ryan Harrison 6-3, 6-4.