(CNN) -- Top seed Serena Williams was humbled in straight sets by Russian Elena Dementieva in the semifinals of the Medibank International tournament in Sydney -- reports the event's official Web site.
Dementieva celebrates her impressive semifinal victory over Serena Williams in Sydney.
Olympic champion Dementieva -- seeded three -- will now face compatriot Dinara Safina, whom she beat to win the gold medal in Beijing, in the final after dropping her serve only once in a superb 6-3 6-1 victory.
American Williams went into the match on the back of her marathon quarterfinal struggle with Danish teenager Caroline Wozniacki late on Wednesday, when she saved three match points before prevailing in a third-set tiebreaker.
"I wasn't moving as I wanted to," Williams told medibankinternational.com.au. "I gave it away more than anything. I made a lot of errors and made her look like a champion, really. I just pretty much gave her the match."
Despite the setback, Williams is adamant she can regain the Australian Open crown she won in 2003, 2005 and 2007.
"I don't think anyone is better than me," she said. "I would feel crazy sitting here being a professional tennis player and saying that someone is better than me."
Meanwhile, Safina managed to contend with extreme heat to see off Japan's Ai Sugiyama to reach her first Sydney final at the fourth attempt.
The world number three and second seed took one hour 45 minutes to defeat world No.29 Sugiyama before clinching a 6-4 7-6 victory. Safina will be bidding for her 10th career WTA title against Dementieva.