LONDON (AP) French Open champion Stan Wawrinka's eight-match winning streak ended at Queen's Club on Wednesday when Kevin Anderson edged him 7-6 (4), 7-6 (11).
It was the South African's fourth successive win over Wawrinka.
Anderson pressured the second seed from the start, holding a break point in the opening game. Although Wawrinka stood firm and held two set points at 6-5, it was Anderson who took the tiebreaker.
In the second set, Wawrinka saved a break point when down 3-2, but Anderson always held an advantage in the tiebreaker. In a tense finale, Wawrinka saved five match points, and held three set points before Anderson finally closed out the second-round match with his 22nd ace.
''I felt a very good serving performance by me today,'' said Anderson, who inflicted Wawrinka's first defeat since he lifted the French Open trophy. Anderson was also the first player to defeat Wawrinka after he won his previous major at the 2014 Australian Open.
''Just kept patient throughout,'' he added. ''I definitely tried to come in quite a bit especially off my serves, trying to take away his block return a little bit.''
Second-seeded Wawrinka was satisfied with his performance against an in-form opponent.
''I think singles was in general good level,'' said Wawrinka, who also played doubles on Wednesday. ''I did one big mistake on the set point, but that's it. In general I think he was playing really well. He was going for his shots and going for the line without really a plan. Just going and putting a lot of pressure.''
Third seeded Canadian Milos Raonic, playing his first event since a short layoff to undergo minor surgery to correct a pinched nerve in his right foot, also reached the quarter-finals with a 6-4, 6-7 (5), 6-1 victory over Frenchman Richard Gasquet.
Raonic took the first set by breaking in the opening game and fighting off five break points to hold for 2-0. After Gasquet leveled by winning the second set in a tiebreaker Raonic dominated the decider, racing to a 4-0 lead and claiming 71 percent of the points.
Seventh-seeded Gilles Simon of France resisted early pressure in each set to defeat Thanasi Kokkinakis of Australia 6-4, 6-2.
Simon lost the first nine points but won the next four games to gain an advantage in the opening set, and after fighting off a break point when down 2-1 in the second, he broke Kokkinakis to lead 3-2. A running backhand winner down the line secured him a second break for 5-2.
Alexandr Dolgopolov failed to follow up his first round upset of Rafael Nadal when the Ukrainian was defeated 6-3, 7-6 (4) by Spaniard Guillermo Garcia-Lopez.