Top seed Maria Sharapova and Serena Williams will meet in Saturday's Australian Open women's singles final after both won their semi-finals.

Sharapova finished off Belgian Kim Clijsters' hopes of winning her first Australian title with a 6-4 6-2 win.

Williams reached her third Open final earlier when she defeated 17-year-old Czech Nicole Vaidisova 7-6 6-4.

Sharapova took one hour, 23 minutes to beat fourth-seed Clijsters, who departed Rod Laver Arena to a standing ovation in what is expected to be her last appearance at the tournament.

Clijsters has flagged her intention to retire at the end of the year.

Sharapova, who will become world No.1 next week, made 33 unforced errors but was still able to seal victory on her first match point.

"I served a few double faults at the wrong time but I was able to get first serves in when I needed to," Sharapova said.

"Serena is playing great tennis and she has won many of these titles before but I will look forward to playing her."

After claiming the first set in 42 minutes, Sharapova raced to a 3-0 lead in the second set.

Clijsters fought back to 2-4 down, and had a chance to break Sharapova's serve for 3-4.

But the Belgian missed her shot, and at 2-5 down double-faulted in her next service game to concede match point - which Sharapova happily took.

Earlier, unseeded American Williams, who won the tournament in 2003 and 2005, needed six match points to beat 10th seed Vaidisova.

Vaidisova saved five match points before Williams finally sealed the match with a smash in 1 hour 46 minutes.

She should have won it on the fifth match point when a service return from Vaidisova was clearly wide but called in.

Williams clenched her fist and ran in to the net. She could have challenged the call via the electronic Hawkeye system - and would have been proved right and won - but had run out of challenges.

Her victory means Williams is on the road back after injuries derailed her seasons in 2005 and 2006.

Winning through to the final means she has moved back into the top 20, after starting the season - just a few weeks ago - ranked 81 in the world.

"I can't believe it, that's awesome, it was so fast," Williams said.

But she admitted she had almost buckled while trying to put away the Czech teenager.

"It was nearly a gagaroony ... basically gagging," she said.

"She played some incredible points on match points, she was so relaxed she reminded me of myself," she said.

It was the first meeting between the pair.

Vaidisova broke serve in the opening game of the match and as Williams skipped chasing a return it appeared as though an ankle problem might have returned.

However she bounced back to break serve in the 10th game and went on to win the tiebreaker 7-5.

The American dominated the final set, breaking serve in the first, third and fifth games to race to a 4-1 lead.

Vaidisova, however, climbed back into contention when she broke in the eighth game and held serve to trail 4-5.

She saved five match points, overcoming the nerves which had led to a spate of unforced errors throughout the bulk of the match.

With the fifth match point a lucky call for the Czech, Williams made no mistake when she seized her next opportunity, rushing to the net to bury an easy smash for the match.

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