MELBOURNE, Australia — In her Grand Slam comeback, Kim Clijsters upset Serena Williams en route to claiming the U.S. Open title.

Williams was really, really upset in that semifinal last September and it cost her the match and a record fine.

Four months later, the return of another Belgian from a premature retirement has bolstered the field at the Australian Open, which starts Sunday, and created a compelling women's draw in the year's first Grand Slam tournament.

Justine Henin, who has won seven Grand Slam singles titles and quit in May 2008 while holding the No. 1 ranking, is only one tournament into her comeback, but is hoping to emulate Clijsters' successful return to the majors.

Again, Williams is the defending champion.

While the men's champion at Melbourne Park is widely expected to come from the group of top five players led by Roger Federer, Rafael Nadal and Novak Djokovic — who've won the last three Australian titles — the list of women's contenders is growing.

Clijsters, a former world No. 1 who married U.S. basketball player Brian Lynch and gave birth to daughter Jada during two years away from tennis, has quickly regained her form. She has won two titles in five tournaments, including the upset of Williams.

Upset being an understatement.

It was a profanity-laced, finger-pointing tantrum directed at a line judge in a semifinal loss to Clijsters at the U.S. Open that cost Williams a record fine of $82,500. She also faces suspension from the U.S. Open if she has any serious outbursts at a major in the next two years.

Williams, winner of 11 Grand Slam singles titles, doesn't want to talk about that anymore, saying after her arrival in Australia that she'd discussed the outburst enough. After almost two months off, it was time to focus on tennis.

"No matter what, I have to be at my best, because whenever I play these young ... ladies," Williams said, "they're always at their best."

Besides Clijsters and Henin, Williams also has Maria Sharapova to contend with this year.

Sharapova won the 2008 Australian Open but was unable to defend her title last year after shoulder surgery kept her off the tour for almost 10 months.

Then there's the other Russians: second-seeded Dinara Safina, a three-time Grand Slam finalist who his returning from a back injury; third-seeded Svetlana Kuznetsova, the reigning French Open champion; and 2008 Olympic gold medalist Elena Dementieva.

The rivalries in the men's draw are already established.

Federer finished his last match in Melbourne Park in tears after a five-set final loss to Nadal cost him a chance of equaling Pete Sampras' record of 14 career Grand Slam singles titles.

In the wake of that defeat, he married longtime girlfriend Mirka Vavrinec, returned to the No. 1 ranking, then won his first French Open title to equal Sampras' mark and complete a career Grand Slam of all four majors. Then after adding to the record by outlasting Andy Roddick in the Wimbledon final 16-14 in the fifth set, he became the father of twin daughters.

But just on the cusp of a third consecutive major, he was upset in the U.S. Open final by 6-foot-6 Argentine Juan Martin del Potro, ending the Swiss player's run at five straight titles in New York.

The win was a boost for del Potro, who displaced Andy Murray at No. 4 last week to ensure he'll avoid the top three players at least until the semifinals at Melbourne Park.

In 2009, Federer lost to Murray in Doha, Nadal in Melbourne and to Djokovic at Miami in March.

Then as Nadal struggled with injury, Federer found his rhythm.

"I got better and better as the season went on," Federer said. "I was able to bounce back and was on a roll. I can do it again. That's a good feeling to have."