Novak Djokovic looked vulnerable for the first time at this Australian Open when Lleyton Hewitt won six straight games to take a set in the last match of a day that had already featured a stunning, upset loss for Serena Williams. Numbers told the surprising story for Williams in her fourth-round loss Monday: seven double-faults, including four in one game; 37 unforced errors, and a first-serve percentage of just over 50 percent 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. 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. 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, played Clijsters in a quarterfinal on Tuesday. Kvitova had some trouble late before beating former top-ranked Ana Ivanovic 6-2, 7-6 (2) Monday and will next next play Sara Errani of Italy, who beat 2008 semifinalist Zheng Jie 6-2, 6-1. In the late-finishing night match, defending champion Djokovic reached the quarterfinals here for the fifth straight year with a 6-1, 6-3, 4-6, 6-3 win over Hewitt, ending Australia's participation in the singles draws. “It's obviously the first match that I've been tested, against the player I expected to be tested,” against, said Djokovic, who is aiming to become only the fifth man in the Open era to win three consecutive majors after collecting the Wimbledon and US Open titles last year. Nobody had taken more than three games in a set off Djokovic in the opening three rounds. He was leading by two sets and a break before Hewitt, who was playing on a wild card entry after his ranking plummeted in an injury-plagued 2011, ended that streak by winning six straight games to force a fourth set. But Djokovic regained his composure to ensure all of the top five men reached the quarterfinals. He will next play No. 5 David Ferrer, who had a 6-4, 6-4, 6-1 victory over Richard Gasquet of France. Earlier, two-time runner-up Andy Murray was leading 6-1, 6-1, 1-0 when Mikhail Kukushkin retired from their fourth-round match with a left hip injury, giving Murray an easy path into the quarters. Murray will next play Kei Nishikori, who had a 2-6, 6-2, 6-1, 3-6, 6-3 win over sixth-seeded Jo-Wilfried Tsonga, the 2008 finalist.
