Serena wins, clinches year-end top ranking

DOHA, Qatar, Oct. 28 (UPI) -- Serena Williams defeated her sister Venus Wednesday at the Sony Ericsson Championships and also learned she would end the year as the No. 1 player in the world.

Williams went into the season-ending event ranked second behind Dinara Safina and needed to post more victories this week than Safina to pass her and claim the top spot. Safina, however, retired from her opening round-robin match Wednesday and gave up a chance to end the season as No. 1 for the first time in her career.

It is the second time Williams has concluded a season ranked on top. She also did so in 2002.

The eight players originally entered in this tournament were divided into two groups and Williams improved to 2-0 in her group by defeating Venus Williams 5-7, 6-4, 7-6 (7-4). Serena is 2-0 in group play and Venus is 0-2.

The other two players in the group containing the Williams sisters, Elena Dementieva and Svetlana Kuznetsova, had the day off.

In the other group, Carolina Wozniacki won over Victoria Azarenka 1-6, 6-4, 7-5 and Jelena Jankovic improved to 1-1 when Safina withdrew.

Safina quit after two games of the first set. She later said a bone in her lower back is, "starting to fracture," and that she has been battling the injury for three months. Safina said doctors have told her she will have to miss about six weeks and may not be ready for the Australian Open in January.