Roddick continued his fine form from Memphis against Gasquet

American Roddick, runner-up in Memphis last month, won through 7-6 (7-3) 6-3 to set up a tie against Ivan Ljubicic.

World number two Rafael Nadal of Spain also reached the last eight, taking just over an hour to secure a 6-1 6-1 demolition of Juan Carlos Ferrero.

The tournament is wide open following Roger Federer's second-round exit.

And left-handed Nadal feels he is in prime form to secure the title, saying: "I am happy with my game right now. I am playing so much better with my backhand."

The victory sets up a match against Argentina's Juan Ignacio Chela, who beat American Michael Russell 6-4 6-4.

I was thinking at the beginning of the second set, if I lose the serve that I am just going to retire Ivan Ljubicic

"He is playing with a lot of confidence," Nadal said of Chela. "I need to play my best tennis because every match in the quarter-finals is tough."

Another man hoping to benefit from Federer's absence is eighth seed Ljubicic, who overcame a knee problem in the second set to beat Argentina's David Nalbandian 2-6 6-4 6-2.

The Croatian believes his knee will hold up in the latter stages of the tournament, even though he came close to retiring during the match.

"I had problems with my knee in the beginning and couldn't run, I couldn't put anything on the right leg," he said.

"I was thinking at the beginning of the second set, if I lose the serve that I am just going to retire.