MELBOURNE, Jan. 25 (Xinhua) -- World number two Roger Federer fought impressively from two sets down to win a dramatic thriller against Czech Tomas Berdych on Sunday to keep his hopes alive of winning a 14th Grand Slam title at the Australian Open.

Roger Federer of Switzerland celebrates after winning the men's singles fourth round match against Tomas Berdych of Czech Republic at the Australian Open tennis tournament in Melbourne, Jan. 25, 2009. Federer won the match 3-2. (Xinhua/Han Yan)  Photo Gallery>>>

    Federer, who is seeking to equal Pete Sampras's record for Grand Slam titles, came through a worrying start and raised up his game dramatically from the third set to claim the match at 4-6, 6-7(4), 6-4, 6-4, 6-2.

    The Swiss will in quarterfinals face Argentine Juan Martin del Potro, who advanced to the Australian Open round of last eight for the first time. He fought back to defeat No. 19 seed Marin Cilic of Croatia 5-7, 6-4, 6-4, 6-2.

    Federer looked rusty from the beginning of his fourth round match with the Czech and had numerous opportunities to seal decisive games in the first two sets, but Berdych used booming serve, sizzling return or winner to halt Federer's momentum.

    However, Berdych's upsurging form suddenly came to a halt in the third set where Federer picked up himself successfully en route to the comeback thriller.

Tomas Berdych of Czech Republic reacts during the men's singles fourth round match against Roger Federer of Switzerland at the Australian Open tennis tournament in Melbourne, Jan. 25, 2009. (Xinhua/Zhou Lei)  Photo Gallery>>>

    Del Potro, who opened the season by winning his fifth career ATP title in Auckland, becomes the youngest Australian Open quarterfinalist since Richard Krajicek in 1992.

    "Of course I'm happy and it's my first time in the quarterfinals here in Australia, and I want to be in the semifinals," said del Potro. "It will be tough for me to play Federer, but I can try to beat him."

    The Argentine, who retired in the second round on his both previous visits here, has now reached two consecutive Grand Slam quarterfinals after last year's U.S. Open.

    Cilic won the opening set in 48 minutes on del Potro's first double-fault of the match. In the second set, del Potro accounted for the only break as he went up 4-3 on Cilic's forehand error.

    In the third set, the young stars exchanged breaks in the fifthand sixth games before del Potro broke in the ninth game again. Hethen served out the 50-minute set. After that, he never looked back.

    Cilic struggled with his serve throughout the three hours and five minutes match, only winning 50 percent of his first serve compared to del Potro's 67 percent.

    Both players had 10 break point opportunities with del Potro converting on six of them compared to Cilic's three.

    In other men's action, American seventh seed Andy Roddick beat Spain's Tommy Robredo and will face the winner of a encounter between Serbia's defending champion Novak Djokovic and 2006 runner- up Marcos Baghdatis from Cyprus.