Kim Clijsters reckons she didn't win three U.S. Open tournaments and 40 titles overall in her career while worrying about the opposition.

She'll take that thought into the Australian Open, where her first-round match Tuesday against Dinara Safina will be a meeting of two former No. 1-ranked players.

Clijsters said Sunday that despite her 7-2 record against Safina, the match against the tall Russian will be a "challenge, but I've played some good matches against her."

As for her opposition, Clijsters says: "I really don't want to waste too much energy on what's happening on other parts of the draw or what's being said around us."

"You really just try to focus on yourself, the way that you're playing, to just put all that energy into what I'm here for, and that's to try to play good tennis."

Serena Williams will not be defending her title due to a foot injury, so the women's championship appears to be wide open with No. 1 Caroline Wozniacki, Clijsters, Venus Williams, last year's finalist Justine Henin, former champion Maria Sharapova and second-seeded Vera Zvonarva all having realistic chances.

Wozniacki begins play in her first Grand Slam as No. 1 when she takes on Gisela Dulko of Argentina in the second match at Rod Laver Arena. She will be preceded by 2008 champion Maria Sharapova, who plays Tamarine Tanasugarn of Thailand.

Also on Monday, fourth-seeded Venus Williams takes on Sara Errani of Italy, while Henin plays qualifier Sania Mirza of India.

"It's a tough first round because Gisela is a very good player, Wozniacki said of Dulko. "She likes to play on this surface. She's getting a lot of balls back. But I'm looking forward to the match and hoping to get a good start."

Like Safina and Jelena Jankovic before her, Wozniacki has risen to the top without a victory in a major and has had to answer many questions about her legitimacy as a true No. 1.

"I've got great results, you don't become No. 1 by winning small tournaments," said Wozniacki, who won six of her 12 career WTA singles titles in 2010. "I don't have to prove anything."

The 20-year-old Wozniacki lost to Slovakia's Dominika Cibulkova in straight sets in the first round of the Sydney International, which followed two straight-set losses to Zvonareva and Clijsters in exhibition events in Singapore and Hong Kong.

Henin is looking forward to yet another homecoming in Melbourne. She lost the final here last year to Serena Williams only three tournaments into a comeback to the tour after 20 months in retirement. She won the Australian title in 2004, retired in the final against Amelie Mauresmo in 2006 and lost to Sharapova in the quarterfinals in 2008, only a few months before she quit.

That made Henin the only woman to retire while holding the No. 1 ranking.

Henin withdrew from all post-Wimbledon events in 2010 with a right elbow injury, but started 2011 in good form by leading Belgium to the Hopman Cup team final in Perth, Australia.

"I'll probably need a few more months to be completely free of the pain," she said Saturday. "It doesn't mean I cannot compete and try to be close to my best or what I can produce. But I need matches, I need rhythm ... but we all know a lot of things can happen."

Henin isn't willing to predict who will be in the women's final on Jan. 29.

"It's the beginning of the season, everyone is fresh mentally, but you need to find the rhythm again of the competition," she said.

"You still have the older generation, I'm part of it ... Kim, Venus of course. Then the new generation is coming up. It's going to be a big battle. We know the few names that can go to the end, but a lot of surprises also happen in Grand Slams."

Clijsters agrees.

"Tough players, new players that you don't expect to be doing well can be on a great run," Clijsters said Sunday. "So many things can happen."