MELBOURNE, Jan 23: Roger Federer and Andre Agassi set up a tantalising quarterfinal showdown between the current and former world number ones after they both emerged victorious at the Australian Open on Sunday.

Federer kept his Australian Open title defence on track with a commanding 6-2 6-2 7-6 fourth-round win over talented Cypriot qualifier Marcos Baghdatis. Agassi, a four-time champion in Melbourne, stayed on course for a possible fifth title with a 6-7 7-6 7-6 6-4 win over big-serving Swede Joachim Johansson.

Another mouth-watering contest is looming in the women's draw after Wimbledon champion Maria Sharapova advanced to the quarterfinals against her fellow Russian and U.S. Open holder Svetlana Kuznetsova.

Sharapova recovered from trailing by a set and a break in the second to overcome Italian Silvia Farina Elia 4-6 6-1 6-2 while Kuznetsova overpowered her compatriot Vera Douchevina 6-4 6-2.

Serena Williams, who completed a non-calendar year grand slam when she won in Melbourne two years ago, was forced to dig deep before beating 11th-seeded Russian Nadia Petrova 6-1 3-6 6-3.

The American will play second seeded Frenchwoman Amelie Mauresmo, a 6-2 6-4 winner over Russia's Evgenia Linetskaya, but said she had a lot of work to do. Marat Safin, runner-up to Federer 12 months ago, kept the Russian flag flying in the men's draw when he clawed back to beat Belgium's Olivier Rochus 4-6 7-6 7-6 7-6 in an epic match lasting three hours 42 minutes.

Safin will play Dominik Hrbaty, who thrashed 2002 champion Thomas Johansson of Sweden 7-5 6-3 6-1. Safin had to work much harder than expected against Rochus and his frustration boiled over in the third set when he smashed a racket, earning himself a code violation and a possible fine.

Federer, who has yet to drop a set in the tournament, had to fight back from 3-0 in his third set tiebreak with Baghdatis to maintain his perfect record going into the second week.

Agassi, the oldest player in the men's draw at 34, withstood a record 51 aces from Johansson to beat the in-form Swede, who smashed 96 winners but still lost. The previous aces record was 49 held by 1996 Wimbledon champion Richard Krajicek of the Netherlands.

Sharapova, 17, appeared out of sorts against an opponent almost twice her age but grew in confidence and finally managed to close out the match. Her meeting with Kuznetsova guarantees there will be at least one Russian woman in the semi-finals although there will be no room for sentiment when they square off.

RESULTS (X DENOTES SEEDING):