SYDNEY (AFP) Elena Dementieva successfully defended her Sydney International title on Friday, leaving Serena Williams with injury concerns just days out from the Australian Open. The Russian fifth seed was always in control of the final, winning 6-3, 6-2 in just 75 minutes but the American world number one was clearly inconvenienced by a troublesome left knee she had strapped for the match. Williams, who is going into next weeks opening Grand Slam as defending champion, favoured the knee and she was unusually subdued during the final. The match ended in an anti-climax with Dementieva holding three match points on Serenas serve and thumping a return winner for the championship. It was Dementievas 15th career title and she became the first player to win back-to-back titles here since Martina Hingis in 2001-02. The Russian has now won six of her last seven finals and it was her fifth victory against Williams in 12 encounters. She beat Williams in the semi-finals of last years event. Dementieva broke Williamss serve five times and dominated the points, 70-47. It is Dementievas first tournament of 2010 and this time last year she had won her opening two tournaments, going on to win her first 15 matches of the season. The defeat continued Williamss run of outs at the Sydney International. It was her first final here after three previous losing semi-final appearances at the tournament. Both players are projected to retain their respective rankings over the next two weeks of the Australian Open, with Williams to remain the number one for 87 weeks and Dementieva staying at five. The Australian Open gets under way in Melbourne on Monday.