Serena falls at Australian Open; Djokovic, Wozniacki advance

All Serena Williams had to do was look at the numbers for an explanation of her stunning loss in the fourth round at the Australian Open.

Seven double-faults, including four in one game; 37 unforced errors, and a first-serve percentage of just over 50 percent Monday that had her convinced "maybe I should have started serving lefty."

Some other numbers indicated why her 6-2, 6-3 loss to Russia's Ekaterina Makarova on what she admitted was a still-sore left ankle was more of a shock, particularly at this stage of the year's first major.

She has played 43 singles matches at Melbourne Park since she won the first of her five Australian Open titles in 2003, and Monday's loss was just her third. She's 54-7 since playing here for the first time in 1998, and she hasn't gone out this early here since 2006.

"I'm not physically 100 percent, so I can't be so angry at myself, even though I'm very unhappy," Williams said. "I know that I can play a hundred times better than I did this whole tournament."

Without Williams, who injured her left ankle in Brisbane two weeks ago, the only major winners still in contention were Maria Sharapova, defending champion Kim Clijsters and Wimbledon winner Petra Kvitova.

Sharapova earned the right to play Makarova in the quarterfinal when she beat Germany's Sabine Lisicki 3-6, 6-2, 6-3 in a night match. The 2008 champion blew a 3-0 lead in the opening set, needed three set points to win the second and advanced on her second match point despite making 47 unforced errors and eight double-faults.

"A lot of ups and downs today — fortunately I finished on a high note," she said. "Even though I didn't play my best tennis I fought to the end and sometimes that's what gets you through."

Top-seeded Caroline Wozniacki, still in search of her first Grand Slam title, plays Clijsters in a quarterfinal on Tuesday. The Belgian advanced to the quarterfinals with a comeback win over Li Na on Sunday in a rematch of the 2011 decider, while Kvitova had some trouble late before beating former top-ranked Ana Ivanovic 6-2, 7-6 (2) Monday.

Kvitova will next play Sara Errani of Italy, who beat 2008 semifinalist Zheng Jie 6-2, 6-1.

In the late match, defending champion Novak Djokovic reached the quarterfinals for the fifth straight year with a 6-1, 6-3, 4-6, 6-3 win over former No. 1-ranked Lleyton Hewitt.

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