BELGRADE, Serbia — Second-seeded John Isner of the United States reached the Serbia Open semifinals Friday, beating Richard Gasquet of France 2-6, 7-6 (6), 6-3.

Gasquet broke twice to win the first set. In the second, Isner saved three break points, forcing a tiebreaker that Gasquet lost after a double-fault.

Gasquet opened the third set with a break, but Isner broke back twice for a victory and his first singles semifinals on clay this year.

Fourth-seeded Stanislas Wawrinka also made it to the semifinals after saving two set points in struggling past sixth-seeded Viktor Troicki of Serbia 7-5, 6-7 (3), 7-6 (6).

Troicki wasted two match points at 6-4 in the third set tiebreaker. Wawrinka then made good on his own match point to finish.