SYDNEY (AFP) - Russian Elena Dementieva stretched her winning streak to nine matches with a dominant straight-sets victory over a subdued Serena Williams to reach the final of the Sydney WTA International on Thursday. The world number four pounded away the winners, only dropped her serve once, and gave the tournament top seed no way out in reeling off a 6-3, 6-1 win in 68 minutes.The victory set up a rematch of last year's Beijing Olympics gold medal final against second seed Dinara Safina in an all-Russian decider on Friday night.Dementieva's form matched the blistering heat as the Olympic champion sent the nine-time grand slam winner crashing out, breaking Williams's serve five times for her third win over the American in seven meetings. Dementieva was coming off a tournament victory in last week's Auckland Classic, where she did not drop a set in five matches and beat compatriot Elena Vesnina in the final. "I've done a lot of good work," Dementieva said. "I think all these big results from last year have really given me a lot confidence. "I'm just playing with lots of confidence, which is great." She said wins over Ana Ivanovic and Svetlana Kuznetsova on the way to taking the Dubai title last February was a major career turning point."The first big change was... winning in Dubai in the beginning of the year, beating lots of good players on this tournament," she said."From then on, I just started to play much better. For sure the big win at the Beijing Olympics was a big step in my career, and just a big goal to achieve."Williams fought a 2 hour and 40 minute struggle with Danish teenager Caroline Wozniacki late Wednesday, saving three match points before prevailing in a third-set tie-breaker. "I wasn't moving as I wanted to today," Williams said. "I gave it away more than anything. I made a lot of errors and made her look like a champ, really. I just pretty much gave her the match."While Dementieva is looking to improve on her lamentable record in the Australian Open, where she hasn't got past the fourth round in 10 attempts, three-time champion Williams is expected to go into the year's first grand slam as the women's favourite. Safina meanwhile battled through intense heat and the resistance of Japan's Ai Sugiyama to reach her first Sydney final at the fourth attempt. The Russian world number three spent one hour and 45 minutes battling the 29th-ranked Sugiyama in 42 degree Celsius (108 Fahrenheit) heat before clinching a 6-4, 7-6 (7/3) victory. Safina will be bidding for her 10th career WTA title against Dementieva. The semi-finalists did not have the sanctuary of the extreme heat policy implemented at the Australian Open, where play for women's matches is suspended once the temperature reaches 35 Celsius (95 Fahrenheit). "I don't know when it was worse, yesterday or today. It was pretty hot even (when) I was warming up before the match outside of the court," Safina said. "I was just standing there, and I was like, I cannot move. But it's not an excuse, because it's (as) hot for her and for me." Safina, last year's French Open runner-up, is enjoying her best results in an Australian campaign and has yet to drop a set this week.