Top seeds eye semis

Roddick has yet to drop a set

Both the men's and women's top seeds are in quarter-finals action at the Australian Open on Tuesday.

Andy Roddick takes on dangerous Russian Marat Safin while Justine Henin-Hardenne faces big-hitting American Lindsay Davenport.

Safin is attempting to fight his way back up the rankings after spending time out because of injury.

But Roddick expects a tough battle, describing Safin as "still one of the top guys, despite his ranking".

The match is likely to be dominated by who serves best, although both also possess booming groundstrokes.

But Roddick, who has not dropped a set in Melbourne so far, will start as favourite to reach the last four.

Defending champion Andre Agassi is also in action and faces Sebastian Grosjean in the last eight.

Tuesday's order of play

Agassi beat the Frenchman in three one-sided sets at the same stage last year and looks likely to extend his unbeaten record at the Australian Open, which stretches back to 1999.

In the women's event, Belgium's Henin-Hardenne has the best all-round game on display

Davenport has plenty of power but Henin-Hardenne has beefed up over the last couple of years and her fine recent form should see her through to the last four.

Tuesday's play gets underway on Rod Laver Court with fourth seed Amelie Mauresmo facing 32nd seed Fabiola Zuluaga.