The eagerly awaited match pitted Davenport, who was 19-1 with three titles since returning to the tour, against a former Grand Slam winner for the first time since she took maternity leave to give birth to son Jagger last June.

"From the day I found out, I started working for this game," Sharapova said of the draw. "I approached it like it's a final."

Locked in and sharp from the start, Sharapova yielded only six points in the first five games, keeping Davenport constantly on the run. Nothing much was going right for Davenport, who saw her serves come back for winners and passing shots zip past when she ventured to the net.

The crowd, which had started roughly divided in their support of the two players, with a sprinkling of American flags scattered around packed Rod Laver Arena, largely shifted to underdog Davenport and cheered loudly when she finally held for her first game to pull to 5-1.

"I wish I could've given them a little more to cheer for," Davenport said. "Obviously I wanted to play a little better than I did in the beginning, but she was really aggressive on me.

"She was head and shoulders better than I was. I felt like I never really hit the ball that well, and I'm in trouble when I'm not hitting the ball well."

Sharapova held to finish off the set in 26 minutes with a crisp backhand cross-court winner.

In the second set, Davenport started showing flashes of the skills that carried her to three Grand Slam titles and the No. 1 ranking. She fended off triple-break point while serving at 3-3 before Sharapova cashed a fourth with a sharply angled backhand service return winner.

Sharapova, who never gave up more than two points in her eight service games, held, then broke Davenport for the fifth time when the American netted a forehand on Sharapova's second match point.

"Obviously I'm disappointed with the way this match went and this tournament went, but I have to look big picture at this point in my career, and so far it's gone pretty well the last few months," Davenport said. "I still feel like I'm the luckiest girl in the world."

Sharapova, who lost last year's final to Serena Williams, finished with 26 winners to just 12 unforced errors.

Williams and top-ranked Justine Henin scored straight-set victories earlier that weren't as easy as the scores indicated to move a step closer to a possible semifinal showdown.

Williams was the aggressor in a 6-3, 6-1 win over Meng Yuan, hitting so hard on virtually every shot that she seemed to be trying to reduce the ball to bits of fluff.

"My game was definitely a good game to play someone like her," said Williams, who prefers to match her power against anyone else's. "I really enjoy the battle. I was able to practice my groundstroke game a lot."

Pushing her record at Melbourne Park to 25-1 since 2003, Williams ran off the last four games, breaking Yuan with a backhand crosscourt passing shot on match point that the Chinese player let drop, only to see it clip the line.

Henin looked to be on her way to an easy victory over Russia's Olga Poutchkova, running through the first set in 22 minutes while committing just five unforced errors.

But the hard-hitting Poutchkova began picking up her game, and Henin appeared to be bothered by the gusty winds that made every service toss an adventure, complicated on one side by a bright midday sun.

Henin had five double-faults in her first two service games of the second set, contributing to nine break points for Poutchkova. Henin had 20 unforced errors to nine winners in the set, but was clearly happy to have survived.

"I played a very good first set, then I lost some intensity," said Henin, who skipped Melbourne last year because she was going through a divorce and had to default in the 2006 final because of a stomach illness.

On the men's side, second-ranked Rafael Nadal breezed to a 6-0, 6-2, 6-2 win over Frenchman Florent Serra.

Unseeded Mardy Fish ousted No. 11 Tommy Robredo, but two other Americans were eliminated: Jesse Levine lost to No. 24 Jarkko Nieminen and Sam Warburg fell to Frenchman Jo-Wilfried Tsonga, who followed his upset of No. 9 Andy Murray by hitting 54 winners and 14 aces in three sets.

No. 4 Nikolay Davydenko, No. 14 Mikhail Youzhny, No. 20 Ivo Karlovic and No. 23 Paul-Henri Mathieu also advanced.