Rafael Nadal and defending champion Novak Djokovic eased into the last eight of the Toronto Masters on Thursday, while a racket-smashing Andy Roddick suffered a shock upset.
Frenchman Gilles Simon, who a day earlier sent world number one Roger Federer tumbling out of the tournament, returned to the court and swept into the quarter-finals with a tidy 6-3, 6-4 win over Argentine Jose Acasuso.
However, number six seed Roddick became the latest upset victim by losing to 19-year-old Croat Marin Cilic 6-4, 4-6, 6-4.
French Open and Wimbledon champion Nadal stopped plucky Russian Igor Andreev 6-2, 7-6 to improve his unbeaten streak to 26 matches.
"I play a very good match, 100 percent better than yesterday," Nadal told reporters. "I was a little bit worried about the second set because Federer happened the same yesterday."
Nadal is on course to meet Djokovic in the semi-finals.
American Roddick appeared baffled by the hard-hitting Cilic, but after dropping the opening set broke at 5-4 to take the second. However, Roddick's momentum stalled in the third and Cilic took control.
Roddick became increasingly frustrated as the match slipped away, smashing his racket and spending parts of the set arguing with the chair umpire.
"Something doesn't feel comfortable," Roddick, playing only his seventh match since injuring his back at the Rome Masters in early May, told reporters.
"It's a little bit across the board. My forehand is just not doing anything. I'm missing it and that's the one that I need to click right now."
Serb Djokovic, playing his first event since Wimbledon, dispatched Swede Robin Soderling 6-4, 6-4 while British eighth seed Andy Murray booked his place in the last eight with a 6-2 0-6 6-4 win over Stanislas Wawrinka.
In another upset, German Nicolas Kiefer toppled fourth-seeded Russian Nikolai Davydenko 4-6, 6-4, 6-4 while Frenchman Richard Gasquet got the better of Spain's David Ferrer for the first time in four career meetings, winning 6-3, 6-3.
James Blake, the last remaining American in the $2.6 million tournament, moved on with a 4-6, 6-1, 6-4 win over Russian Dmitry Tursunov.