Amelie Mauresmo reached her second Australian Open final when Kim Clijsters was forced to retire, with the Frenchwoman leading 5-7 6-2 3-2.
Clijsters was already struggling with the back and hip injuries she carried into the tournament when she turned her ankle midway through the third set.
The US Open champion received treatment and attempted to carry on but retired after one more point.
Mauresmo, the 1999 finalist, will face Justine Henin-Hardenne in the final.
It will be the 27-year-old's first appearance in a Grand Slam final since she lost to Martina Hingis at Melbourne Park seven years ago.
"It's such a long time. I'm very happy to do it again," she said. "Hopefully it'll go my way this time."
Of the sudden end to her encounter with Clijsters, Mauresmo added: "It's very strange. We had such a great battle till she twisted the ankle.
"It's a little bit of an unfinished match. I hope she gets better and it's not too bad but that's the way it is."
"It's very frustrating because I felt in that third set I was playing better again"
Clijsters' retirement might have come as something of a relief to the Frenchwoman, who was struggling to put away her below-par opponent.
Mauresmo lost the first set, having led by a break, and then - after levelling the match easily - she squandered another break advantage in the decider before Clijsters landed awkwardly on her right ankle.
Mauresmo, seeded third, committed 33 unforced errors, while Clijsters contributed 47 in a nervy match.
Clijsters' only consolation is that she will replace Lindsay Davenport as world number one when the new rankings are released on Monday.
The Belgian said she felt she could have gone onto win the match against Mauresmo had she not hurt her ankle.
"I got myself back into the match in the third set," she said.
"I ran around my backhand, tried to hit an inside-out forehand and I went over on my ankle. I felt it straight away.
"It's very frustrating because I felt in that third set I was getting into it and playing better again."