After taking a tumble on match point, Serena Williams got up and whipped a backhand winner down the line to finish off her second-round match at the Australian Open and her 500th career win.

With the 6-0, 6-4 victory over Barbora Zahlavova Strycova on Thursday, Williams extended her winning streak to 16 matches at Melbourne Park, where she won back-to-back titles in 2009 and ‘10 but couldn’t play last year due to injury.

Her participation had been in doubt again after she badly sprained her ankle two weeks ago at a warmup tournament, which is why the Rod Laver Arena went quiet when Williams fell onto the court in the penultimate rally and sat, watching, as Zahlavova Strycova’s shot floated out.

“It’s fine. I just have wobbly ankles,” she said in a TV interview after the match. “I wasn’t meant to be a ballerina or anything.”

Her 500th match win was something she’d wanted to achieve since her older sister, Venus, passed the milestone.

“I knew I had to get there too, because I do everything she does,” she said. Venus Williams, a seven-time Grand Slam winner with career win-loss record of 598-147 as a pro, is not playing the Australian Open to recover from illness.

Serena Williams also has 104 losses in her career.

After racing through the first set in 22 minutes, her ankle got a good workout in the second set. She was leading 5-2 until the Czech player held and then broke back in the ninth game. After falling behind 40-0 in the last game, Williams won five straight points to avoid another game.

Maria Sharapova, one of the other two former champions in the draw, reached the third round after just two hours on court.

The 2008 champion had a 6-0, 6-1 second-round win over U.S. qualifier Jamie Hampton in 64 minutes, two days after beating Argentina’s Gisela Dulko by the same margin.

Sharapova did not play in any warmup events and spent nearly two weeks in Melbourne ahead of the season’s first major while she rested an injured left ankle.

“It was more about getting my feet going ... worrying about myself,” Sharapova said. “Yeah, started my preparations in the offseason a little late, took a bit of extra time in practice instead of rushing into a tournament.”

She’ll meet No. 30 Angelique Kerber, who beat Canada’s Stephanie Dubois 7-5, 6-1.

Seventh-seeded Vera Zvonareva, a two-time semifinalist at Melbourne Park, had a 6-1, 7-6 (3) over Lucie Hradecka. No. 21 Ana Ivanovic also advanced, beating Dutch player Michaella Krajicek 6-2, 6-3.

Two seeded players were ousted, with Sara Errani beating No. 29 Nadia Petrova 6-2, 6-2 and No. 25 Kaia Kanepi’s strong start to the season coming to an end in a 6-2, 7-5 loss to Ekaterina Makarova of Russia.

On the men’s side, 2008 finalist Jo-Wilfried Tsonga advanced to the third round when he beat Ricardo Mello of Brazil 7-5, 6-4, 6-4.

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