Wednesday, Quarterfinals

Rod Laver Arena
Sara Errani (ITA #48) vs. [2] Petra Kvitova (CZE #2)
Head-to-head: first meeting
On Tuesday, Caroline Wozniacki's defeat to Kim Clijsters saw her become the first player to drop out of the four-way battle for the WTA's No.1 ranking. Her loss leaves Petra Kvitova in pole position to replace her at the summit. But before the 21-year-old Czech can contemplate this, she must first see off one of the Australian Open's surprise packages, Sara Errani.

Prior to the tournament, Errani had never been beyond the third round at a major, but the super-fit 24-year-old has thrived in the Melbourne heat, dropping just one set in four matches. Particularly impressive was her 62 61 dismantling of former semifinalist Zheng Jie, who had no answer to Errani's mixture of unerring consistency and excellent court coverage. Whether these traits are enough to disarm an on-song Kvitova remains to be seen, and the Italian's fortunes may rest on her ability to turn the match - scheduled first up on Rod Laver - into a battle of endurance under the midday sun.

Ekaterina Makarova (RUS #56) vs. [4] Maria Sharapova (RUS #4)
Head-to-head: Sharapova leads 2-0
For much of Ekaterina Makarova's seven years as a professional, she has lived in the shadows of her more fêted compatriots. And none have been more celebrated than her next opponent, three-time Grand Slam champion Maria Sharapova. However, on Monday, it was Makarova's turn to spend some time in the limelight, as she sent shockwaves around Melbourne Park with a 62 63 win over five-time champion Serena Williams.

If Makarova wants to be more than just a footnote in the story of this year's Australian Open, though, she will need to follow up this career-best performance with another upset. And to do this, the 23-year-old Muscovite will need to serve well; Sharapova has been averaging six service breaks a match, and if she maintains this standard on Wednesday she will be tough to beat. Yet Makarova is no slouch on the return herself - she broke Serena five times - and this, allied with her counterpunching style, ensures she remains a very live underdog.