Serena Williams upset by Petrova in Madrid Tennis

MADRID: Top-ranked Serena Williams was knocked out of the Madrid Masters, falling 4-6, 6-2, 6-3 to Nadia Petrova of Russia in the third round.

Petrova had 10 aces and frustrated Williams into making 41 errors.

In the men''s draw, second-seeded Rafael Nadal advanced to the third round with a 6-4, 6-3 win against Ukrainian qualifier Oleksandr Dolgopolov Jr. American Andy Roddick withdrew due to illness ahead of his opening match.