Associated Press

MELBOURNE, Australia — Rafael Nadal limped out of the Australian Open complaining his leg was too sore to challenge Fernando Gonzalez in the quarterfinals. With Gonzalez stinging winners past him from both the forehand and backhand sides, though, even a fit Nadal might have struggled.

The 10th-seeded Gonzalez had 41 winners in a 6-2, 6-4, 6-3 upset over the second-seeded Nadal on Wednesday, earning him a semifinal spot along with top-ranked Roger Federer, Andy Roddick and Tommy Haas.

In the women’s semifinals, the unseeded Serena Williams was to continue her unlikely quest for an eighth Grand Slam title. Limited to only four tournaments last year by recurring knee problems, Williams was not expected to be a serious contender at this year’s Australian Open.

But she was one win away from the final, as was top-seeded Maria Sharapova — who reached the semis with a 7-6 (5), 7-5 win over Anna Chakvetadze, a fellow 19-year-old Russian.

Williams was to face 17-year-old Nicole Vaidisova of the Czech Republic in the first semifinal, followed by Sharapova against fourth-seeded Kim Clijsters.

French Open champion Nadal was the only player to beat Federer at this stage of a tournament last year, doing it four times in finals. Federer was 91-1 against everyone else — his only other loss an upset to Andy Murray at Cincinnati.

It was a five-setter against Murray on Monday that Nadal thinks derailed his prospects of making the Australian Open final.

“I can’t run a lot,” he said Wednesday.

Roddick is only 1-12 against Federer, but the 24-year-old American had match points against Federer at the Masters Cup last November and beat him in the final of an exhibition tournament at Kooyong on Jan. 14.

Clijsters reached the women’s semis by defeating Martina Hingis 3-6, 6-4,

6-3 on Wednesday. Hingis’ comeback run from three years in retirement ended last year in a quarterfinal loss to Clijsters, who also beat her in the same stage at the French Open.

Clijsters has reached the semis in every trip she’s made to Australia since 2002, and has bowed out to the eventual champion every time.

Sharapova was brilliant at times and woeful at others against Chakvetadze, mixing 32 winners with 41 unforced errors and dropping serve twice in each set. She also was fined for coaching, after the chair umpire warned her for communicating with her father, Yuri, while serving at 2-2 in the second set.

Sharapova lost to Clijsters in an exhibition final at Hong Kong earlier in the month.