HOUSTON (AP) Qualifier Ivo Karlovic of Croatia boomed 24 aces and ended a 3-hour, 16-minute match with a close line call for a 7-6 (2), 6-7 (2), 7-6 (9) victory over fourth seeded John Isner on Friday in the quarterfinals of the U.S. Men's Clay Court Championship.
The 6-foot-10 Karlovic - the talles player on the ATP Tour - is accustomed to using his height for a good service advantage, but felt he was looking in a mirror against the 6-9 Isner, who had 23 aces.
Tied at 9-9 in the final tiebreaker, Karlovic slammed home his final ace and ended it with a forehand drive that clipped the line. Ryan Sweeting of the United States, gained his first career semifinal with a 3-6, 6-3, 6-1 victory over Teymuraz Gabashivili of Russia.