World number two Roger Federer fought back from two sets down to snatch a dramatic 4-6, 6-7, 6-4, 6-4, 6-2 victory against Tomas Berdych Sunday, retaining his hopes of winning a 14th Grand Slam title at the Australian Open.
Federer, who is seeking to equal Pete Sampras's record for Grand Slam titles, appeared listless from the beginning of his fourth round match with the Czech, before he found his form in the middle of the third set and never looked back.
The Swiss second seed had numerous opportunities to seal decisive games in each of the opening sets but the 20th-seeded Berdych managed to find a booming serve, blistering return or a winner to halt Federer's momentum.
However, after Berdych missed a smash while 3-4 down in the third, Federer seized the initiative and drastically raised his game to take the match in three hours, 29 minutes, setting up a quarter-final with Argentine Juan Martin Del Potro.
Martin del Potro stops Cilic
Eighth seed Martin del Potro clinched the first of the men's quarter-final spots with victory over Croatia's Marin Cilic.
The Argentine put a slow start behind him to advance 5-7, 6-4, 6-4, 6-2.
Roddick blasts his way into last 8
American Andy Roddick beat Tommy Robredo 7-5, 6-1, 6-3 in the fourth round , extending his perfect record against the Spaniard to 10 matches.
The seventh seed, who has only conceded one set to Robredo in their 10 meetings, overwhelmed him again to wrap up a comprehensive victory in one hour and 47 minutes.
Roddick, 26, has made the semi-finals three times at Melbourne Park in his seven previous visits but has yet to make the final.
His quarter-final opponent on Tuesday will be either defending champion Novak Djokovic or 2006 runner-up Marcos Baghdatis.
Defending champion Djokovic through
Serbia's Novak Djokovic kept alive his Australian Open defence with a 6-1, 7-6, 6-7, 6-2 fourth-round win over Marcos Baghdatis of Cyprus that stretched into the early hours of Monday.
Djokovic, steadily growing in confidence with each match of the tournament, raced through the opening set in 25 minutes then fought back from a break down to win the second in a tiebreak.
Baghdatis, a finalist at Melbourne Park three years ago, won the third in a tiebreak but twice failed to hold his own service games in the fourth set as Djokovic finally sealed victory at 2.26 a.m. local time.
Third-seeded Djokovic's opponent in Tuesday's quarter-finals will be American Andy Roddick, who advanced safely with a 7-5 6-1 6-3 win over Spain's Tommy Robredo.