Even on one good leg, Venus Williams is tough to beat at Wimbledon.

The five-time champion wore a strap on her left knee yesterday but still advanced to the third round by beating Kateryna Bondarenko of Ukraine 6-3, 6-2. In the men's draw, No. 5 Juan Martin del Potro of Argentina became the highest seed to be eliminated so far, losing in straight sets to Lleyton Hewitt of Australia.

Tournament favourite Williams has been hampered by knee trouble in the past, but there was no indication of a problem this week until she walked on to sunny Court 1 bandaged from mid-calf to mid-thigh.

Williams let out a yelp when she appeared to pull up on a backhand in the third game, perhaps because of the knee. Otherwise she moved across the grass freely, charging forward to pounce on short balls. She won 17 points at the net to two for Bondarenko.

Coyed

Williams was coy about the reason for the tape.

"Just for support," she said twice in response to questions.

Her mother and coach, Oracene Price, declined to discuss the matter. Williams wore the strap again later when she and sister Serena beat Virginie Razzano and Aravane Rezai in doubles, 6-3, 6-3.

In men's play, two-time runner-up Andy Roddick lost serve only once and defeated Igor Kunitsyn 6-4, 6-2, 3-6, 6-2.

"It was comfortable most of the time," Roddick said. "I played my best set by far in the fourth set."

Roddick will next play No. 26 Jurgen Melzer, the Wimbledon boys champion in 1999.

Hewitt, who won Wimbledon in 2002, beat del Potro 6-3, 7-5, 7-5 to break an 11-match losing streak against top-five players.

Hewitt was broken for the first time when serving for the match at 5-4 in the third set, but broke right back. He then double-faulted on his first match point in the next game before del Potro sent a shot long on the second.

Del Potro has a history of struggling on grass, and also lost in the second round the previous two years at Wimbledon.

No. 3 Andy Murray, trying to become the first British man since 1936 to win Wimbledon, defeated Ernests Gulbis 6-2, 7-5, 6-3. Fabrice Santoro's 14th Wimbledon ended with a loss to former No. 1 Juan Carlos Ferrero, 6-7 (1), 6-3, 6-4, 6-3.

No break point

Joining Williams in the women's third round was French Open champion Svetlana Kuznetsova, who beat Pauline Parmentier 6-1, 6-3 in 59 minutes. The Roland Garros runner-up, top-ranked Dinara Safina, never faced a break point and beat Rossana de Los Rios 6-3, 7-5.

Last year's French Open winner, No. 13-seeded Ana Ivanovic, beat Sara Errani 7-5, 6-1. No. 17 Amelie Mauresmo, the 2006 Wimbledon champion, beat Kristina Kucova 6-3, 6-3. No. 18 Samantha Stosur, a Roland Garros semifinalist this month, swept the last five games to beat qualifier Tatjana Malek 4-6, 7-6 (6), 6-4.

Safina and Kuznetsova criticised the court assignments. Kuznetsova was on Court 3, while Safina and former No. 1-ranked players Ivanovic, Mauresmo and Jelena Jankovic were also on smaller courts.

"Of course it's not fair," Safina said. "Hopefully, next match I'll play on bigger court."

The only women's match on Centre Court was ninth-seeded Caroline Wozniacki win over Maria Kirilenko.