MELBOURNE, Australia — For Kim Clijsters, it was one injury too many.

For Amelie Mauresmo, it meant a long-awaited second chance at a Grand Slam title.

The second-seeded Clijsters, who'll assume the No. 1 spot when the new rankings come out next week, retired after she sprained her ankle in the third set of her semifinal match Thursday against third-seeded Mauresmo.

Mauresmo was leading 5-7, 6-2, 3-2 and 15-love when Clijsters hobbled to the net and withdrew, ending the prospect of an all-Belgian final with eighth-seeded Justine Henin-Hardenne.

Henin-Hardenne, seeking a fifth Grand Slam singles title, earlier extended her Melbourne Park winning streak to 13 matches by ousting No. 4 Maria Sharapova of Russia 4-6, 6-1, 6-4.

"It's a shame it had to happen," Clijsters said before heading to a hospital to have the ankle examined. "I think it was going to be a close one. Whenever I have a problem, I'm not going to quit for nothing."

But this time, the pain was way too great for Clijsters, already suffering coming into the match. Combined with hip and back pain, she had trouble with her left hamstring from compensating for the ailments.

It looked as though she might win in straight sets as Mauresmo, known for making mistakes when things get tight, showed her nerves again.

Serving at 5-6, she fended off four set points before double-faulting on the fifth to hand Clijsters the first set.

As the match wore on, Clijsters looked increasingly stiff, but started hitting the ball better again in the third set.

After breaking Mauresmo to get back on serve and going up 40-0 in the fifth game, Clijsters let Mauresmo back in with two unforced errors and a double-fault.

Facing a breakpoint, she stumbled and fell when Mauresmo hit a forehand behind her. Clijsters had her ankle heavily taped in the changeover and only played one more shot before retiring.

"A very strange way to finish a match," Mauresmo said. "We had such a great battle ... it's a little bit of an unfinished match, but that's the way it is sometimes. I just hope she's going to get better."

Henin-Hardenne beat Clijsters in the final here in 2004, but was sidelined by injuries last year.

She won the Sydney International the week before the Open, coming back after two months out with a hamstring injury, and is now 10-0 this season.

"It's been tough for me to be injured for such a long time, and then coming back in my first Grand Slam, being again in the final, I think it's just an amazing feeling," Henin-Hardenne said. "I really enjoy that right now."

Third-seeded Mauresmo hasn't returned to a Grand Slam final since Martina Hingis beat her for the 1999 Australian Open title. She had reached the semifinals of four other majors, three times at Wimbledon, then finally managed a breakthrough win at the season-ending WTA Championship in November

"I can (hardly) remember I made the final here," Mauresmo said jokingly. "For all those years, I've been working hard, adjusting a few things here and there to try to do my best."

With the Rod Laver Arena roof closed due to a return of Melbourne's recent heat wave, every point between Henin-Hardenne and Sharapova was a struggle. Each produced some outstanding defensive pickups and strong, clean winners.

"I think we played a great match. It was very intense physically, especially in the first set," Henin-Hardenne said,

She dropped that set, then never allowed the increasingly discouraged Sharapova to hold serve in the second.

Sharapova looked toward her father and coach, Yuri Sharapov, after nearly every point, shouting to him after Henin-Hardenne broke her to go ahead 4-2 in the last set.

The usually confident Sharapova looked tight and unsettled, whacking the ball into the net after mistakes and kicking it once.

Sharapova pumped her fist after breaking Henin-Hardenne — who was serving for the match — to get back on serve at 4-5 in the third.

But the woman who has credited her mental toughness for getting her through big matches then collapsed in a string of backhand errors.

Henin-Hardenne sealed it on her first match point with one of her trademark one-handed backhand winners down the line.

Sharapova, the 2004 Wimbledon champion, reached the semis at three of the four Grand Slams last season and lost to the eventual champion at all four.

"I'll be seeing headlines: Maria can't get past the semis; Maria can't finish it in the third set," Sharapova said. But, "I think it was a good match. I didn't come in the best prepared ... without many matches, to be able to play the quality of tennis I was able to play today is a big plus."

This Australian Open combination marks the first time since computer rankings were introduced in 1975 that four former No. 1-ranked women reached the semis at a Grand Slam event.