Li hits her way into Australian Open quarterfinals

9th seed Li Na, one of last year's Australian Open semifinalists, demonstrated on Sunday why she is one of the players to beat for the Melbourne championship. Hitting with steady authority on both sides, and taking thoughtful care in her shot selection, Sydney champion Li managed 8th seed Victoria Azarenka in straight sets. The 6-3, 6-3 win was one of the most impressive on the women's side, so far. Li has become more aggressive than she used to be, but she's also leaving more margin for error than she used to. That's a nice combination.

Top seed Caroline Wozniacki also won her round of 16 match in straight sets. Wozniacki defeated Anastasija Sevastova 6-3, 6-4. As always, the Great Dane let her opponent hit more winners--and make many more errors.

And now we come to Maria Sharapova, who looked like she was in comeback mode in her excellent match against Julia Goerges. But the 14th seed hardly looked that way against Andrea Petkovic. In fact, Petkovic served for the match at 6-2, 5-1, but was broken. Sharapova held, and there was reason to believe that she about to fight her way back into the match. After all, Petkovic has been known to melt away at a big moment. The 30th seed, however, was able to close the set at 6-4 and advance to the quarterfinals. Sharapova made thirty unforced errors to Petkovic's nine, and--though she kept her double faults down to five--simply did not look like she was on a comeback path.