Now that the first week – and the opening three rounds – of the 2010 Australian Open are over, it’s time to examine what seasoned hands call the “business end” of the tournament, a time when the summer charms of Australia take a back seat to the pursuit of a major championship and some hefty bumps in prize money.

The year’s first leg of the Grand Slam series exploded with action in the middle of the first week before taking a breather on Saturday. Now that week two is at hand, tennis fans should once again expect some sensational slugfests in Melbourne Park.

Today, we’ll look at the remainder of the women’s field.

The bottom half of the draw, which starts the fourth round on Sunday (Australia time, of course), features tests of body and mind. The battle of bodies is a Belgian affair, as seven-time major champion Justine Henin drags a somewhat weary frame to the court against countrywoman Yanina Wickmayer, a 2009 U.S. Open semifinalist who hasn’t lost a match this year.

Henin needed 2 hours and 50 minutes to turn back fifth-seeded Elena Dementieva in a second-round heavyweight bout, and she then had to labor for three more sets in a draining third-round win over No. 27 Alisa Kleybanova. Henin’s match against Dementieva was a night match, and her contest with Kleybanova was a day match, so the former world No. 1 had a relatively short turnaround between her previous two matches.

This fourth-rounder against Wickmayer will be a night match, which will give Henin several extra hours for her body to recuperate. If Henin is appreciably fresh, and isn’t hampered by the strain of competition after spending more than a year away from the WTA Tour, she should win. But if the older Belgian is sluggish and tired, the younger Wickmayer owns the punishing groundstrokes that can run Henin ragged.

Nadia Petrova

The main test of the mind comes in that same section of the women’s draw, as two volatile and erratic Russians – Nadia Petrova and Svetlana Kuznetsova – will try to see who can maintain poise and composure for a longer period of time. Both of these women – longtime fixtures in the top 20 (Kuznetsova in the top 10) – get down on themselves at the drop of a hat.

They must maintain a high level of belief even when the flow of the match works against them. The fact that they’ll be playing each other should calm their nerves to a certain extent, but in the final analysis, the realm of mental toughness should decide their match more than any X-and-O considerations.

Whoever emerges from that portion of the women’s draw – Henin, Wickmayer, Petrova, Kuznetsova – will have an excellent chance of reaching the final. In the top half, there’s only one name to keep track of, and that’s Serena Williams.

The defending Australian Open champion, who is also the No. 1 player in the world, faces tests that are tricky, but not worrisome. Australia’s Samantha Stosur will receive crowd support in Monday’s fourth-round match, but Serena is clearly a superior player.

If Serena takes care of business at each stage of the tournament, her toughest pre-final test would likely come against sister Venus Williams, who must get past a credible opponent, 17th-seeded Francesca Schiavone, in the round of 16. Venus could play No. 4 Caroline Wozniacki in the quarterfinals, but it’s hard to see how the diminutive Dane can match Serena’s power in a potential semifinal. An all-Williams semi is the best possible matchup the top half of the draw can provide.

In terms of the quality of each player left in the women’s draw, Serena and Henin are the class of the field. But if fitness becomes an issue, Wickmayer could surprise a lot of people. And if the Russian contingent displays poise under pressure, Kuznetsova could do some major damage to the rest of the bracket in Melbourne.