Defending champion Maria Sharapova's pullout from the Australian Open narrows the field of realistic contenders, with Jelena Jankovic, Ana Ivanovic and the Williams sisters leading the title hunt.

The Russian superstar was hampered by a right shoulder injury for much of last season, skipping the Beijing Olympics and the US Open before having surgery in October, and she is still not confident of her fitness levels.

Sharapova's absence is a blow for organisers who will miss her glamour, but it opens the door for a new champion.

Serbia's Jankovic is world number one despite never winning a Grand Slam, and could be poised to go the distance after crashing in the semis to Sharapova last year.

But a bout of flu that forced her out of her only warm-up tournament in Hong Kong could hamper her chances.

"It's disappointing because I take care to try to play some matches and try to work on my game and try to get ready for the big Grand Slams, but sometimes it's bad luck. What can I do?" she said.

Fellow Serb Ana Ivanovic, who lost to Sharapova in last year's final, was bundled out of the Brisbane International last week in the quarterfinals by Amelie Mauresmo.

The French Open champion knows she has to knuckle down to get back in her groove.

"Unfortunately, I didn't find my best tennis in Brisbane, but it was a good work-out and I have a lot to work to do," she said.

The effervescent 21-year-old needs a lift after a poor second half to last season.

After winning her first Grand Slam at Roland Garros, she lost 10 out of 20 matches and won only one title, a tier-two event in Linz.

Veteran Serena Williams is searching for her 10th Grand Slam title and few would bet against the American pulling off another major win.

The reigning US Open champion and world number two will bring her usual exuberance to Melbourne, as well as a new line of clothing.

"I want 2009 to start off in a great way. I have been working hard and I am really looking forward to the new season," said Williams, who pulled out of the Hopman Cup with an injury but is playing this week at the Sydney International.

Her sister Venus, the world number six, will also be a threat and is in fine form with wins over two top 10 players — Jankovic and Russia's Vera Zvonareva — in Hong Kong last week.

The seven-time Grand Slam champion said she was feeling good about her chances.

"Every season is different. You always feel different. It's just knowing how to handle those different emotions that come with life. So far so good," she said.

"I feel good (about this season). I know that it's mind over matter. You just tell yourself that you feel good even if you don't and it works. Fortunately I do feel good."

Russia's Dinara Safina is also well placed to make her Grand Slam breakthrough after climbing to third in the world rankings at the end of 2008.

She heads to Melbourne in the best physical shape of her career with big brother Marat Safin, who won the Australian Open in 2005, tipping her to lift the women's title.

"I think she is ready," he said.

"There are going to be a lot of nerves, she's not defending anything because she lost first round last year, but she has a huge chance."

Russians Elena Dementieva, who won in Auckland last week, Svetlana Kuznetsova and Vera Zvonareva will also be in the race for the two million Australian dollar winners cheque.