China's Zheng Jie said she was brimming with confidence for the 2012 Olympics back at Wimbledon after an impressive performance on Centre Court that almost got the better of Serena Williams.

Zheng will represent her country at the All England Club in London later this month and, if she maintains her form, will be a dangerous prospect in the draw.

The 28-year-old took the first set off four-time champion Williams but lost a final set thriller in a 6-7 (5), 6-2, 9-7 defeat on Saturday.

The 25th seed provided the American with a serious test over nearly 2-1/2 hours, but Williams finally made the breakthrough through some record-breaking serving.

"She is a very good player, and I played very close in that match," Zheng said. "I think it gives me more confidence for the Olympics, and also I'm so happy to come back to the Centre Court and many guys came to support me and gave me the power to fight."

In 2008, Zheng became the first Chinese player to reach a grand slam semifinal, before Williams halted her progress. The Sichuan Province right-hander came so close to exacting revenge.

"I really wanted to win this match, because I remember this is my third time against her at Wimbledon, the Centre Court," Zheng said.

"So that also gave me more confidence looking forward to the Olympic Games."

Williams said Zheng was playing "unbelievable on grass" - and the Chinese said she had told her as much to her face.

Praise indeed from one of the game's greats, who has four singles and five doubles titles in total from the only grand slam played on the green surface.

Williams fired 23 aces - a Wimbledon women's singles record - to make it into the last 16.

China's Peng Shuai, the 30th seed, is the only Asian player left in the singles.

The 26-year-old plays Russian 17th seed Maria Kirilenko today, having beaten Arantxa Rus of the Netherlands 6-1, 6-2 in round three.

Peng won their last clash, in Beijing in 2006.

Zheng will still be around for the second week of Wimbledon, to contest the mixed doubles third round with her Indian partner Rohan Bopanna.

The 10th seeds are yet to play, having had a bye in the first round and a walkover in the second.

Peng, Zheng and Li Na are all in the Olympic women's singles draw. Peng and Zheng will team up for the doubles, while Li will compete alongside Zhang Shuai.