Serena goes out, Nadal progresses in China

Serena Williams was knocked out of the third round of the $6.6 million China Open by Nadia Petrova on Thursday, leaving the WTA's event without a top three seed in the quarter-finals.

The American, who will retake the number one spot next week, lost 6-4, 3-6, 7-6 in a hard fought contest against the Russian 13th seed to join her third seeded sister Venus and top seed Dinara Safina in exiting the tournament.

Men's top seed Rafa Nadal was delighted with his form and fitness after earlier negotiating a tricky second round tie against American James Blake to reach the last eight.

Nadal, playing his first tournament since picking up an abdominal injury at the US Open was not at his rampaging best but certainly proved his fitness by outlasting Blake 7-5, 6-7, 6-3.

"I felt I played really well all the match, one of my best matches since the injury of the knee," said Nadal, who missed his Wimbledon title defence because of tendinitis of both knees.

"He's a very good player. I think he has one of the best returns of any player I have played," he added.

Blake, ranked 24th after missing part of the season through injury, hit the ball low and hard throughout the match but errors on key points allowed the Spaniard to tie up their career head-to-head at 3-3.

The New Yorker refused to back down throughout the contest and saved a match point before winning the second set in a tiebreak, only to hand the world number two a 5-3 lead with a double fault in the decider.

"Winning in three sets always gives you confidence but today what really gives me confidence is how I played," said Nadal, who will meet Russian Marat Safin for a place in the semi-finals.

Former world number one Safin, who plans to retire at the end of the season, proved there was still life in his injury-wracked body with a 6-3, 6-4 win over seventh seed Fernando Gonzalez.

"He served unbelievable and didn't let me do too much, one break point in the whole match," said Chilean Gonzalez, champion here two years ago.

"After that he was the only player on the court. I wasn't playing bad but I wasn't playing much," he added.

In the women's draw, the third round proved a step too far for China's world number 226 Zhang Shuai, the lowest ranked player to beat a world number one when she upset Safina in the second round.

The wildcard went down 6-1, 6-4 to France's Marion Bartoli, who will next play Vera Zvonareva after the Russian seventh seed outlasted 10th seeded Italian Flavia Pennetta 6-3, 5-7, 7-5.