MELBOURNE, Australia (AP) - Serena Williams finally beat Maria Sharapova in a big match, saving three match points and defeating the Wimbledon champion 2-6, 7-5, 8-6 Thursday to advance to the women's final at the Australian Open.

Williams weathered a barrage of deep groundstrokes and shrieks in the first set and at the start of the second by Sharapova before picking up the pace on her serve and getting her forehand working.

The 17-year-old Sharapova, who upset Williams in the Wimbledon final and in the season-ending WTA championship last season, served for the match at 5-4 in the second set and again at 5-4 in the third.

The seventh-seeded Williams has won 13 consecutive matches at Melbourne Park and is one match away from a seventh Grand Slam title.

''I think it definitely lived up to expectations,'' said Williams of her showdown with Sharapova. ''It was a lot of fun … I can't believe it's over, I feel like I should still be playing.''

The third set lasted 66 minutes, and the crowd in the packed Rod Laver Arena cheered and groaned on every point, seemingly not wanting the drama to end.

After twice trading breaks earlier in the set and saving match points with a string of blistering forehands, Williams saved three break points before holding in the 13th game, setting up game point with her first serve-and-volley approach in 2 hours, 33 minutes.

She dropped to her knees and punched the air repeatedly when she set up two match points of her own with a winner in the next game.

After finishing off the match with a backhand after 2:39, Williams leaped all the way to the net.

In 2003, Williams saved two match points in a semifinal against Kim Clijsters before reaching the final and beating her older sister, Venus, for the title.

''Two times in a row back from match point down …. this is such a special court for me,'' said Williams.

In Saturday's championship match, Williams will face the winner of the later semifinal between top-ranked Lindsay Davenport and 19th-seeded Nathalie Dechy of France.

''I have to stay focussed. I'm back in a final,'' Williams said. ''It's been such a tough 12 months for me. I want to thank everyone so much, especially back home.''

Williams blamed her Wimbledon loss on nerves because she was coming back from a long time off the circuit because of injuries. But she was tight from the beginning on Thursday, spraying shots into the net, long and wide. She had 13 unforced errors in the first five games alone.

Williams couldn't seem to believe her inaccuracy, testing her swing after mistakes, shaking her head and even laughing.

Sharapova needed only four winners in the first set, earning two service breaks as she blunted most of Williams' power and then only needed to keep the ball in play.

In the first game of the second set, a ballboy bounced a ball at Williams and she smacked it into the stands in pure frustration after losing a point to let Sharapova back to 30-all.

Williams started to match Sharapova's squeals with her own grunts on the big shots.

After putting away a leaping overhead winner to close the third game of the second set, Williams pumped her arm and yelled ''Yes! Come On!'' from between clenched teeth.

She hit the fastest serve of the women's tournament at 124 mph to hold after saving a break point with another powerful overhead in the seventh game. And again she grunted ''Yes!''

Williams broke Sharapova's serve in the 11th game of the second set and held to even the match at one set apiece.

She looked fitter in the deciding set as Sharapova, who had a tough, three-set win over compatriot and U.S. Open champion Svetlana Kuznetsova in the quarterfinals, struggled again in the heat.

Top-ranked Roger Federer meets No. 4 Marat Safin on Thursday night for a place in Sunday's men's final. Federer beat Safin in the 2004 final.

Andy Roddick was leading 6-3, 7-5, 4-1 when Nikolay Davydenko retired from their quarterfinal after just 1:35 Wednesday because he was having trouble breathing.

That was less time than Roddick's semifinal opponent, Lleyton Hewitt, needed for the fifth set alone before getting past Argentina's David Nalbandian 6-3, 6-2, 1-6, 3-6, 10-8 in 4 hours, 5 minutes.

Hewitt's marathon win ensured the top four seeded men made the semifinals at the Australian Open for the first time since 1988, and at any Grand Slam tournament for the first time since Wimbledon in 1995.

''It's the top four players in the world playing the semifinals here … so you're going to have to play your best tennis,'' Hewitt said. ''And you're going to have to have enough petrol in the tank.''

The Roddick-Hewitt semifinal is set for Friday night.