LONDON (AP) -- Australian Open champion Stan Wawrinka continued his quest for a fourth title this year by beating Marinko Matosevic of Australia 7-5, 6-3 to reach the semifinals of the grass-court Queen's Club tournament, a warm-up event for Wimbledon.
The top-seeded Wawrinka, who along with his victory at the Australian Open has also claimed titles in Chennai and Monte Carlo this season, will next play fourth-seeded Grigor Dimitrov. The Bulgarian advanced with a walkover when eighth-seeded opponent Alexandr Dolgopolov defaulted with a right thigh injury sustained in a second round doubles match late Thursday.
Spanish left-hander Feliciano Lopez held off a strong second set challenge to upset second-seeded Czech Tomas Berdych 6-4, 7-6 (7).
Lopez next plays another Czech, Radek Stepanek, who rallied after dropping the first set to beat seventh-seeded South African Kevin Anderson 1-6, 6-3, 6-2.
Wawrinka took time to gain the upper hand against Matosevic, who fought off three break points but then double-faulted at 6-5 to gift Wawrinka the only break of the first set.
Wawrinka then earned an early advantage in the second set, with a break to lead 2-0 deciding the outcome.
Tenth-seeded Lopez had to work hard for his victory, edging the opening set after breaking to lead 3-2 on his fifth break point.
In the second set, Berdych failed to convert a break point to lead 3-1 and then held three set points in the tiebreaker at 6-3 and another at 7-6 before double-faulting on his opponent's first match point.
''Very close, very close,'' Lopez said of the match.
Anderson fired seven aces and broke 15th-seeded Stepanek twice to take the opening set. But a break for 2-0 by Stepanek decided the second set, and two breaks in the third earned the Czech his first ATP Tour semifinal place since Memphis in February 2012.
''For a half hour I really had no chance. He hit every shot perfectly,'' said Stepanek.