Third seed Caroline Wozniacki and 2004 champion Maria Sharapova passed tough third-round tests in straight sets to make the last 16 at Wimbledon.

Wozniacki took the first set against Russia's Anastasia Pavlyuchenkova with a decisive break in the 12th game.

The Dane finally hauled a see-saw second set her way, with another late break carrying her to a 7-5 6-4 win.

Sharapova shook off a tenacious Barbora Zahlavova Strycova 7-5 6-3 to set up a match against Serena Williams.

It will be the first meeting between Sharapova and Serena at Wimbledon since the Russian upset her as a fast-rising 17-year-old in the 2004 final.

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Wozniacki, 19 and ranked fourth in the world, narrowly avoided a first-set tie-break courtesy of some wayward shots from Pavlyuchenkova in the final rallies of their opener.

Pavlyuchenkova responded with a break in the first game of the second, but miscued from a deep, flat backhand from Wozniacki in the fourth to wipe out her advantage.

Pavlyuchenkova's serve then cracked again in the final game to bring an end to her stubborn resistance.

Sharapova showed the sort of steely resolve during big points that her compatriot lacked.

The 23-year-old lost her opening service game in both sets but each time fought her way back to overhaul an aggressive Zahlavova Strycova.

The Czech had kept the umpire busy with a series of challenges and complaints before her racquet bore the brunt of her frustration as she found the net at break point down in the 12th.

Sharapova moved ahead in the second set with a hard-earned break in the sixth and, after facing down a break point in the following game, clinched the contest with an ace.

"I love playing against her," said Sharapova of her match against Serena.

"She is the defending champion. She is great on this surface. She has won numerous Grand Slams. If there is a challenge ahead of you, it is definitely playing against her, and I enjoy that."

Poland's Agnieszka Radwanska also had to work hard as she overcame Italy's Sara Errani 6-3 6-1.

The Polish seventh seed's progress could have been more seriously threatened had Errani converted any of the five break points she earned in the opening set.

Hopes of an upset were extinguished in the second as the Pole raced through to book a fourth-round meeting with China's Li Na.

Kvitova had lost her previous two meeting with Azarenka

Victoria Azarenka became the eighth of the top 20 women's seeds to fall as she disintegrated 7-5 6-0 in the face of a ruthless performance from Czech Petra Kvitova.

The Belarussian 14th seed had set point at 5-4 up in the opener but did not win another game after squandering that chance.

Some searing groundstrokes from her unseeded 20-year-old opponent made light of the 51 ranking places that separated the pair.

A double fault from Azarenka was an appropriate end as the second set slipped past her in 32 minutes.

Kvitova, who has never been beyond the first round at Wimbledon in two previous attempts, will now face Wozniacki.

Azarenka was soon followed out of the tournament by Flavia Pennetta, who was comfortably beaten 6-2 6-3 by Klara Zakopalova of the Czech Republic.

The tenth seed suffered an early exit at Eastbourne in the run-up to Wimbledon and looked well short of form.

Zakopalova is deep into unchartered territory after winning only once in six previous campaigns at the All England Club.

Kaia Kanepi's impressive run continues as she saw off Romanian 31st seed Alexandra Dulgheru 6-1 6-3.

The Estonian, ranked 80th in the world, knocked out Australian sixth seed Samantha Stosur in the first round.

Li made her way through in relatively straightforward style and was rarely troubled in a 6-1 6-3 victory over Australian Anastasia Rodionova.

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