Third seed Nikolay Davydenko wore down Czech Tomas Berdych to seal a 5-7, 6-4, 6-1, 7-6 victory and reach the Australian Open quarter-finals on Monday.

The Russian was outplayed by the 13th seed in the first set but his unerringly consistent game gradually nullified the 21-year-old Berdych and he clinched victory on his fourth match point in exactly three hours.

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Berdych saved three match points at 5-6 in the fourth set to force the tiebreak but he made two unforced errors to give Davydenko match point and another mistake sent the Russian through to the last eight.

Davydenko will play German Tommy Haas for a place in the semi-finals.

Haas revived memories of former glories at Melbourne Park when he beat Argentine eighth seed David Nalbandian 4-6, 6-3, 6-2, 6-3.

The German, who took his career record against the South American to 3-0 and is a two-time semi-finalist atthe Australian Open, used crisp strikes from the back of the court to frustrate Nalbandian and win through in two hours and 29 minutes on Vodafone Arena.

"As soon as I got that second set under my belt I felt pretty confident," said the former world number two in a news conference.

"He played really solid at the beginning of the first set, which started to worry me a little bit because he barely made any mistakes, especially on the backhand side. He was playing extremely well."

After losing the first set in 44 minutes, Haas broke early in the next two to take control of the match against a man who had been on court over nine hours for his three victories in the tournament.

He broke again in the Argentine's opening service game of the fourth set and in the final ninth game, wrapping up victory when a Nalbandian forehand drifted wide.

The 28-year-old's career has been set back by a series of injuries, including breaks to both ankles, and he was delighted to be in the thick of things in the second week of a Slam again.

"I was aggressive, I kept focused pretty well. (I am) obviously very pleased to beat David and be in the quarter-finals here again," he said.

Sharapova edges out Zvonareva

Top seed Maria Sharapova edged out Vera Zvonareva 7-5, 6-4 to reach the Australian Open quarter-finals for the third time in her career on Monday.

The 19-year-old Russian broke in a tough game 12 of the opening set to take the initiative and despite recovering from 5-2 down in the second, the 22nd seed could not fend off Sharapova, who won in an hour and 46 minutes on Rod Laver Arena.

Sharapova, a semi-finalist the last two years at Melbourne Park, plays her third fellow Russian of the tournament in the last eight when she faces 12th seed Anna Chakvetadze.