MELBOURNE -- After cruising through so far, the big guns in the women's draw face their first real tests as the Australian Open begins two days of quarterfinals on Tuesday.

Both the men's and women's singles tournaments remain wide open after a week of contrasting results but the quarterfinals will offer the first real clues into picking the winner.

There have been no surprises in the women's draw until now with seven of the top eight seeds making it through to the quarterfinals.

The only player to miss out was fifth seed Serena Williams, who withdrew from the tournament just before her first match because of an ankle injury.

Italy's Adriana Serra Zanetti was the main beneficiary of Serena's absence, scrambling through the weakest section of the draw to make her first grand slam quarterfinal.

However, it is unlikely she will progress much further after being pitted against three-time champion Martina Hingis in the first of Tuesday's two women's quarterfinals.

Hingis is only playing her second tournament since an ankle operation last October cost her the No. 1 ranking. She has not lost a match yet and was in ominous form last week, winning each of her first four matches in straight sets.

The winner of that match will play either Venus Williams or Monica Seles in the semifinals. Williams and Selesmeet in the night match.

Like Hingis, Seles has won each of her matches in straight sets. Williams has been troubled by a knee problem and was pushed to three sets by 13th seed Magdalena Maleeva in the third round.

Seles is already a four-time Australian Open champion but it is Williams, who is chasing her first title in Melbourne, who is the tournament favourite this time.

The powerful American has won four of the last six grand slam tournament's she entered and has beaten Seles 10 of the 11 times they've met.

"Yes, I have a good record against her, but this is a grand slam," Williams said. "It's a different feeling going into a grand slam when you're playing someone like Monica, who has won quite a few and who is a great competitor.

"You have to respect her as a competitor and a person."

While the women's matches have been predictable, the men's draw has been full of surprises with none of the world's top eight-ranked players still in the tournament.

None of the world's top six even made it past the second round because of a combination of injuries and poor play, leaving the draw wide open.

In the first of Tuesday's two men's quarterfinals, Thomas Johannson played Jonas Bjorkman in all Swedish affair.

Johannson is the 16th seed and the favourite to reach the final but will have his work cut out by Bjorkman, who demolished British number one Tim Henman in the fourth round.

"I think Jonas is playing the best tennis of his life and it is going to be a great match," Johansson said.

"We are very, very good friends so it's going to be tough to play but we are fighting for a place in the semis."

The second quarterfinal is the unexpected match-up between Jiri Novak and unseeded Austrian Stefan Koubek.

Novak had to recover from two sets down to beat second-round opponent Francisco Clavet while Koubek has staged two amazing recoveries.

He survived a match point in the third round of his first match against French qualifier Cyril Saulnier and also came from two sets down to beat James Blake in his second match.

"I was pretty much out of the tournament in the first round because I was down pretty bad, but now I'm playing great tennis and looking forward to the next round," Koubek said

"As soon as you start winning some matches you get confident and that's what's happening now with me."