Top seeds show vulnerability in Melbourne

Kim Clijsters remains the favorite to win the Australian Open, but she has already had one of the troublesome matches which haunt her from time to time. She struggled against Alize Cornet, and--though the outcome of the match was hardly in doubt--it wasn't a good day for the third seed. Does Clijsters have her stumble out of the way now, or are there more to come?

2nd seed Vera Zvonareva looked a bit flat against Lucie Safarova. Her next opponent is Iveta Benesova, who has already upset two Russian seeds. Benesova is a talented player who has calmed down a bit in the last couple of years, though her really good results are still in doubles. Zvonareva is the clear favorite in this match, but--if Benesova's serve is in fine tune--the 2nd seed will have to work a bit harder.

Some fans thought Justine Henin could win the tournament, but she was defeated in the third round by an in-form Svetlana Kuznetsova. Sam Stosur was a favorite, too, but she was defeated in the third round by Petra Kvitova. Top seed Caroline Wozniacki should have a fairly easy time of it in the round of 16, when she plays Anastasija Sevastova. But--assuming she advances--her quarterfinal opponent is likely to be 23rd seed Kuznetsova, who--if she plays the way she did in the third round--is likely to upset Francesca Schiavone. (But you never know.) The Russian player had some significant foot pain in her last round, it should be noted.

2010 semifinalist and 9th seed Li Na has quietly advanced to the round of 16, in which she will play 8th seed Victoria Azarenka. Neither of them is a huge favorite to win the Australian Open, but neither of them should be discounted, either. And now, suddenly, 14th seed Maria Sharapova has inserted herself into the drama, and if she defeats Andrea Petkovic, she will get either Li or Azarenka.

Any discussion of the deep end of the draw has to include Petra Kvitova, whose next opponent is Flavia Pennetta. Kvitova's pattern is to lose matches she should win, then--after suffering a losing streak--win something really big. Last year, she made it to the semifinals at Wimbledon and lost to eventual champion Serena Williams. Her defeat of Stosur has to be taken somewhat seriously, especially since Kvitova also won in Brisbane this month. If the entertaining, flat-hitting Czech gets past Pennetta, she will most likely be looking across the net at Vera Zvonareva in the quarterfinals.

Are the "favorites" to win still the favorites? Who is most likely to cause another upset?