BRISBANE, Australia (AP) — One thought entered Serena Williams’ mind as she sprawled across the baseline after injuring her ankle: “Not again!”

Yet another Australian Open campaign is in doubt due to injury — she missed the 2002, 2004 and 2011 editions because she was hurt. In between, she has won five Australian titles and lost only twice at Melbourne Park.

In her first tournament since losing the U.S. Open final in September, Williams was serving for the match with a 6-2, 5-3 lead against Bojana Jovanovski of Serbia on Wednesday when she twisted her left ankle and crashed heavily to the court.

The 13-time Grand Slam winner lay near the baseline for several minutes while getting medical attention. She was helped to a courtside chair and had the ankle re-taped before resuming the second-round match.

Williams limped through the next game, wincing in pain after at least two points, before securing a 6-2, 6-4 win to advance to the Brisbane quarterfinals in her first trip Down Under since winning the 2010 Australian Open title.

She withdrew from the Brisbane tournament later Wednesday after having medical scans which confirmed a sprained ankle “that I probably shouldn’t play on.”

“I’m going to take a couple of days off — not too many — and see how I feel,” Williams said in a statement. “I’m still hopeful of playing the Australian Open.”

Williams has spent a total of 123 nonconsecutive weeks at No. 1 in the women’s rankings in a stellar career that has been punctuated by illness and injuries.

The Australian Open starts Jan. 16. Williams was unable to defend her title in Melbourne last year because she was recovering from two operations on her foot and blood clots in her lungs that kept her sidelined for almost a year after the 2010 Wimbledon tournament.

She returned and won two tournaments heading into the U.S. Open in August but, after losing the final to Sam Stosur, Williams didn’t play another tournament last year due to injuries.

Williams said she was starting to gain confidence after beating South African Chanelle Scheepers in straight sets in the first round at Brisbane and was coasting against Jovakovski, who turned 20 on New Year’s Eve, before she lunged awkwardly and rolled over on her ankle.

Injured again, she said, “I was like, ‘No way.’”

Williams usually wears a protective guard on her left ankle, but took it off during the second set because it was irritating another minor injury on her foot. She said it was a silly mistake.

Her scheduled quarterfinal rival, Daniela Hantuchova of Slovakia, advances directly to the semifinals.

Other results Wednesday were overshadowed by the injury to Williams, who hobbled into a post-match news conference with her ankle heavily strapped and initially said she was “anticipating it’ll be OK.”

“I’m always thinking I can play on, but at the same time I don’t want to stress it out right now,” Williams said.

The scans showed otherwise, casting serious doubt over her fitness for the first major of the season with only two matches in almost four months.

U.S. Open champion Stosur was eliminated in the match on center court immediately before Williams went on, while men’s top seed Andy Murray was only two points from defeat in the second set before he rallied to beat Gilles Muller of Luxembourg 4-6, 7-6 (4), 6-0 in the last night match to move into a quarterfinal against Marcos Baghdatis.

Stosur lost to Iveta Benesova 6-4, 6-2 to extend her run of never advancing beyond the second round at her home tournament.

The No. 54-ranked Czech had never taken a set off Stosur in four previous matches but now finds herself in a quarterfinal match against Australian Open champion Kim Clijsters.

“Hopefully it was just a bad day and I will bounce back next week and the week after,” Stosur said. “It’s not the ideal start but I am not going to panic and think it’s all lost.”

For the second consecutive night, Murray was below par until Adrenalin kicked in, overriding the aches and pains of his offseason training.

Muller took the match to him until he missed a routine volley to start the tiebreaker, which Murray controlled after picking up four set points with a stunning, scrambling backhand from near the baseline.

“That point was a big one and it gave me more confidence in my movement. Sometimes it takes a big point like that to get yourself going,” said Murray, who has lost the last two Australian Open finals and is still aiming to break a drought for British men in Grand Slam tournaments that dates to 1936.

Copyright 2012 The Associated Press.