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 a left hip injury. I put a lot of stress on myself when I do that.'' The world No. 13 will face American qualifier Rhyne Williams on Friday night. Williams ousted wild-card Marcos Baghdatis of Cyprus 6-7 (7), 6-4, 6-2 in Thursday's nightcap to reach his second ATP quarterfinal. Nishikori was trailing Teymuraz Gabashvili of Russia 4-2 when he decided to stop the match. More...