WIMBLEDON, England(AP) Roger Federer has reached his 21st consecutive Grand Slam semifinal by beating Ivo Karlovic 6-3, 7-5, 7-6 (3) at Wimbledon.

Federer used brilliant returns to break the hard-serving Karlovic once in each of the first two sets Wednesday and took advantage of the Croat's poor net play in the tiebreaker. The Swiss star set up four match points with a backhand pass and converted the second with a forehand winner.

Federer never faced a break point against the 6-foot-10 Karlovic, who had not lost serve in his first four matches at Wimbledon.

Federer is trying for his sixth Wimbledon championship and record 15th Grand Slam title.