VIENNA — Ivo Karlovic advanced to his 10th quarterfinal of the season by defeating Sergiy Stakhovsky of Ukraine 6-4, 7-5 at the Erste Bank Open on Wednesday.
The seventh-seeded Croat avoided break points in the second-round match and conceded just nine points in his 11 service games.
Karlovic next plays Ernests Gulbis. The 117th-ranked Latvian, who was on a five-match losing streak coming to this tournament, upset third-seeded John Isner 6-4, 4-6, 6-4 to reach his third quarterfinal of the year.
In a match dominated by strong serving, Gulbis hit 23 aces against the American's 16.