Second-seeded Ivo Karlovic advanced to the semifinals at the Hall of Fame Tennis Championships for the second straight year, beating Germany's Dustin Brown 7-6 (3), 6-3 on Friday.
The 36-year-old Karlovic, from Croatia, was a runner-up to Leyton Hewitt last year.
Coming off a reaching the round of 16 at Wimbledon, the 6-foot-11, hard-serving Karlovic had 23 aces, ending the match with one down the middle at 133 mph.
Karlovic will face No. 4 seeded Jack Sock, from the U.S., after he advanced when qualifier Jan Hernych, of the Czech Republic, retired with an injury in the second game.
Brown upset Rafael Nadal earlier this month in the second round at Wimbledon.