BRISBANE, Australia (AP) — Serena Williams’ Australian Open preparations took a major hit Wednesday when she injured her left ankle and withdrew from the Brisbane International.

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 when she twisted her 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 and losing the next point to surrender a service break to Jovanovski.

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 2010, when she won her fifth Australian Open title.

She withdrew from the Brisbane tournament later Wednesday, saying that tests “confirmed that I have a left ankle sprain (and) 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.”

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

U.S. Open champion Sam Stosur was eliminated in the match on center court immediately before Williams went on.

In the last night match, 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 to move into a quarterfinal against Marcos Baghdatis.

Williams hobbled into a post-match news conference with her ankle heavily wrapped 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.

Even if Williams’ ankle heals, her fitness for the year’s first Grand Slam tournament could be an issue given that she’s only played two matches in four months.

The Australian Open starts on Jan. 16 in Melbourne. Williams missed the 2011 Australian Open while she was recovering from two operations on her foot and blood clots in her lungs that kept her sidelined for about a year after the 2010 Wimbledon tournament.

She 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 her first thought when she sprawled to the court near the baseline on Wednesday was “not again.”

“That’s what I felt,” 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.

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

It was the 28-year-old Benesova’s fourth win over a top-10 player.

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. “I don’t want to dwell on it.

“It’s not the ideal start but I am not going to panic and think it’s all lost.”