Roddick may choose not to defend his Lyon title next week

Berdych, seeded 11, edged a tight first set that was dominated by big serving, and eased to a 7-6 (9-7) 6-3 win.

Roddick went over on his ankle during the second set and was on the verge of withdrawing, but played out the match.

Swiss top seed Roger Federer was made to work hard as he beat Swede Robin Soederling 7-6 (7-5) 7-6 (8-6).

Defending champion Rafael Nadal produced his customary brand of explosive tennis to overpower Germany's Tommy Haas 6-4 6-3.

The last surviving Spaniard in the draw, he now meets Berdych in the last eight.

Robby Ginepri beat seventh seed Tommy Robredo 6-3 7-6 (7-3), and Marat Safin beat Kristof Vliegen 6-3 6-2.

I'm not sure of the upside of trying to play on a bum ankle Andy Roddick

Fernando Gonzalez also went through when his opponent, Joachim Johansson, withdrew ahead of their match with a throat infection.

Roddick admitted he might not be fit to defend his title in Lyon next week, with the end-of-season Masters Cup in Shanghai looming.

"It's the same ankle problem as earlier," said Roddick. "I tweaked it again. It's a problem which I think happened early in the second set.

"Next week's in doubt and Shanghai is the priority. I'm in pretty good (qualifying) shape right now (provisional fourth).