SYDNEY, Australia — Top-seeded Serena Williams lost 6-3, 6-1 amid a flurry of errors against Olympic gold medalist Elena Dementieva in the Sydney International semifinals Thursday.

The second-ranked Williams, who saved three match points in her three-set quarterfinal win over Caroline Wozniacki of Denmark late Wednesday, will head to Melbourne for next week's Australian Open.

"I gave it away more than anything," Williams said. "I made a lot of errors and made her look like a champ, really. I just pretty much gave her the match."

The nine-time Grand Slam singles winner remained optimistic about her chances at the season's first major, saying she is feeling fit and healthy.

"It was good to have a few matches under my belt getting ready for Melbourne," she said. "I feel like I'm going play a lot better than what I did this week."

Dementieva will face fellow Russian and third-ranked Dinara Safina for the Sydney title, a rematch of the Beijing Olympics final.

"I realize how tough it's going to be to play against Dinara tomorrow," Dementieva said. "She's in great shape right now. But it's going to be a great experience anyway. This is what we're all here for. We just want to get the best preparation as possible and play our best in the grand slam."

The Russian has noticed improvement in her game over the past year, notably following wins in Dubai in early 2008 and her Olympic triumph.

"I've done a lot of good work. All these big results from last year really gives me a lot confidence," Dementieva said.

Second-seeded Safina won the earlier semifinal, beating Japan's Ai Sugiyama 6-4, 7-6 (3), but said she still had room for improvement.

"It's going to be a good challenge, especially before the Grand Slam, to play somebody who's in the best shape," she said. "You cannot really play tactically with them. You just have to go out there and hit the ball."

Players have struggled with the heat in Sydney this week, and Thursday afternoon temperatures soared above 104 degrees.

But loud thunder cracked above during the the second set of the women's semifinal. The heavy rain that followed delayed the start of play in the quarterfinals match between Australian Lleyton Hewitt and fourth-seeded David Nalbandian of Argentina.

In the evening session, top-seeded Novak Djokovic of Serbia will play Mario Ancic of Croatia, followed by third-seeded Frenchman Jo-Wilfried Tsonga and Jarkko Nieminen of Finland.