LONDON - Serena Williams' path to Olympic tennis gold will look less daunting to the American after her sister Venus suffered a shock third-round exit on Wednesday.

When Serena kicked off the last 16 action at Wimbledon with a 6-1, 6-0

demolition of Vera Zvonareva on Centre Court, the Williams sisters were still on course to meet in the semi-finals.

Venus had been just as dominant as her younger sister in the first two

rounds of the Games and, as a five-time Wimbledon champion, would have been confident of beating Germany's Angelique Kerber on Court Two.

But seventh seed Kerber produced a dynamic display to win 7-6 (7/5), 7-6 (7/5) and leave Serena relieved she won't have to play Venus with a place in the final on the line.

Instead, Serena will face Denmark's Caroline Wozniacki, who defeated Daniela Hantuchova 6-4, 6-2, in the quarter-finals before a possible last four meeting with Kerber or world number one Victoria Azarenka.

Serena, twice a doubles gold medallist with her sister, can now focus on her bid for a first singles gold medal without the fear of having to lock horns with Venus.

"I think I played better today and even in my second round than any match I played at Wimbledon," she said.

"I was just playing unbelievable. I felt good. I was relaxed. I felt like 'I'm here to have fun, I have nothing to lose. No pressure on myself'."

Venus's exit was the biggest shock so far in this year's Olympic tennis tournament, but she had only herself to blame after a sloppy performance featuring 36 unforced errors and seven double-faults.

Even when the three-time Olympic gold medallist got herself in a commanding position in the first set tie-break, after moving 5-2 ahead, she was unable to take advantage and Kerber was just too tough to crack in the second tie-break.

"I made a few errors and she hit a few winners, things can go quickly in tennis if you don't hold onto it," Venus said.

"I was disappointed to lose the first set but she had a lot of answers. She has had a great year and I have to give her credit for playing well."

There were no such problems for reigning Australian Open champion Azarenka, who defeated Russian 16th seed Nadia Petrova 7-6 (8/6), 6-4.

Elsewhere, Kim Clijsters won the battle of the former world number ones as the Belgian defeated Serbia's Ana Ivanovic 6-3, 6-4.

Clijsters is playing the penultimate tournament of her career as she prepares to retire for the second and final time after next month's US Open and she has admitted an Olympic medal would be the perfect way to sign off.

The 29-year-old, competing in the Olympics for the first time, remains on course to fulfil that dream after cruising past former French Open champion Ivanovic in 58 minutes at Wimbledon.

Four-time Grand Slam champion Clijsters, ranked 36th, will face world

number three Maria Sharapova, who battled back to beat Germany's Sabine Lisicki 6-7 (8/10), 6-4, 6-3.

Petra Kvitova, the 2011 Wimbledon champion, is enjoying another good run at the All England Club.

The Czech sixth seed defeated Italy's Flavia Pennetta 6-3, 6-0 to book a quarter-final meeting with Russian 14th seed Maria Kirilenko, who beat Germany's Julia Goerges 7-6 (7/5), 6-3.

(AFP)