MELBOURNE, Jan 25 A roar of relief marked Roger Federer's comeback from two sets down at the Australian Open on Sunday while women's world No 1 Jelena Jankovic was mute and ineffectual in a fourth-round defeat.

Melbourne Park shook with an explosion of home-town roars, however, when Yugoslav-born Australian wildcard Jelena Dokic buried years of personal pain to reach the quarter-finals of the first Grand Slam of the year.

The 25-year-old, whose split from domineering father Damir and subsequent struggle with severe depression and injuries was played out in front of the world's media, wiped tears from her eyes after her 7-5, 5-7, 8-6 win over Russian Alisa Kleybanova.

“I'm just really fighting,” Dokic said. “I'm really determined and fighting. That's sometimes what keeps it going.

“I think [my coach] might have a few drinks tonight. I think I might as well,” she smiled.

Swiss Federer dug himself out of deep trouble against Czech Tomas Berdych, prevailing 4-6, 6-7, 6-4, 6-4, 6-2 to keep alive his hopes of a record-equalling 14th Grand Slam crown.

“I fought as hard as I could, tried to weather the storm...he pushed me to the limit,” the second seed smiled courtside afterwards.

“I enjoy those kinds of fights because they don't happen very often. I am still in great shape, feel like I could play another couple of sets so that's a good sign.”

He next meets Juan Martin del Potro.

There were no good signs for Jankovic who was blown off court by French typhoon Marion Bartoli 6-1, 6-4.

“When I'm on the top of my game it's very hard to beat me, because you really have to kind of spill blood if you want to win the match,” Jankovic mused afterwards.

“But at the moment, I'm not there yet. I still need to get better, to improve, be much, much tougher out there. Nobody likes to lose. Today was a tough day for me.”

Jankovic's tough day was a jubilant one for Bartoli.

“I knew I could beat Jelena on a good day, it was just a matter of executing,” she told reporters.

Bartoli next plays Vera Zvonareva after the seventh seed beat 10th-seeded fellow Russian Nadia Petrova 7-5, 6-4.Bartoli's Gallic good fortune almost continued on centre court when France's Alize Cornet was poised for victory over third-seeded Russian Dinara Safina, but Cornet melted in the sun.

She twice failed to serve out the match and squandered two match points in the 10th game as Safina turned up the heat to snatch victory.

Safina, whose brother Marat Safin saved a match point in the semi-finals against Roger Federer before winning the Australian Open men's title in 2005, will play Dokic in the quarter-finals on Tuesday.

“Maybe she was just not ready to win this match, because she had it all in the hands,” Safina said when asked if it had been her experience which had seen her safely through.

“I'm just a little bit disappointed about this match, you know. Playing against this girl and allowing myself to do these kinds of mistakes.

“The game is there. I just don't know what's going on through my mind. Somebody [should] smack me so hard in my head that something shakes finally and I put the cables together.”

Men's seventh seed Andy Roddick needed nobody to knock sense into him, with the American in superb form as he beat Tommy Robredo 7-5, 6-1, 6-3.

Roddick, who has conceded only one set to Robredo in their 10 meetings, overwhelmed him again and his quarter-final opponent on Tuesday will be defending champion Novak Djokovic.

The Serbian third seed had to wait for Dokic to finish her match and did not complete his victory over Marcos Baghdatis until the small hours of Monday.

His 6-1, 7-6, 6-7, 6-2 win was completed at 2.26am local time.

Baghdatis is no stranger to late finishes. Last year he lost to Lleyton Hewitt in a third-round match which ended at 4.34am.

Sunday's results (prefix number denotes seeding)

Men's singles

Fourth round 3-Novak Djokovic (Serbia) bt Marcos Baghdatis (Cyprus) 6-1, 7-6 (7-1), 6-7 (5-7), 6-2; 2-Roger Federer (Switzerland) bt 20-Tomas Berdych (Czech Republic) 4-6, 6-7 (4-7) 6-4, 6-4, 6-2; 7-Andy Roddick (US) bt 21-Tommy Robredo (Spain) 7-5, 6-1, 6-3; 8-Juan Martin Del Potro (Argentina) bt 19-Marin Cilic (Croatia) 5-7, 6-4, 6-4, 6-2.

Women's singles

Fourth round Jelena Dokic (Australia) bt 29-Alisa Kleybanova (Russia) 7-5, 5-7, 8-6; 7-Vera Zvonareva (Russia) bt 10-Nadia Petrova (Russia) 7-5, 6-4; 3-Dinara Safina (Russia) bt 15-Alize Cornet (France) 6-2, 2-6, 7-5; 16-Marion Bartoli (France) bt 1-Jelena Jankovic (Serbia) 6-1, 6-4.—Reuters