SYDNEY -- Top-ranked Serena Williams came from a set and 5-2 down to beat Avarane Rezai 3-6, 7-5, 6-4 on Thursday and move into a Sydney International final against defending champion Elena Dementieva.
Rezai was serving for the match at 5-3 in the second set but reigning Australian Open champion Williams won the next five games to even it and go up a break in the third.
Rezai of France recovered breaks in the first and seventh games of the third set but Williams broke her to lead 5-4 and then served it out.
"Was I down that far? I didn't even realize," Williams said. "I don't think she lost her way at all. I felt like I literally lifted my game at that point, because I knew I was going to be headed to Melbourne if I didn't.
"I kept thinking, 'I want to get a little more practice, and I'd hate for it to end now."
Williams has won 35 titles, including the Australian Open, Wimbledon and the season-ending championship last season, but has never reached the Sydney final, held in the week leading up to the year's first major.
"Cool ... finally," she said, relishing the opportunity to gain match fitness and touch in her first tournament of the year.
"That was good because she played really hard, like a top player. That was really good preparation."
Williams, winner of 11 Grand Slam singles titles, will play Friday against Olympic champion Dementieva, who beat sixth-seeded Victoria Azarenka of Belarus 6-3, 6-1.
"I expect a tough match. She's a great champion," Dementieva said of Williams. "I just hope it's going to be a good match for both of us, and good preparation for the Open."
Rezai, a 22-year-old who is ranked 27 and won two WTA titles last year, felt she wasted an opportunity to beat Williams.
"For me, she was not too impressive," Rezai said. "Of course she's a good player, of course I respect her. But I could have won today. I wasn't impressed.
"Probably it was more difficult for her to play against me. I know she's a fighter but I am also a fighter.
"Today I lost. Probably next time I will win."
Former Australian Open finalist Marcos Baghdatis beat former No. 1 Lleyton Hewitt 4-6, 6-2, 6-3, ending Hewitt's attempt for his fifth Sydney title. In the semifinals, Baghdatis will play American Mardy Fish, who beat Australian Peter Luczak 7-6 (5), 6-2.
The Australian Open starts Monday in Melbourne.