Serena Williams returns to the WTA Championships with the Wimbledon and U.S. Open titles, plus the Olympic gold medal, yet with no chance of finishing the year as the No. 1 in the world.
Williams has not played since beating top-ranked Victoria Azarenka in the U.S. Open final in September and her sparse schedule is one of the reasons she won't have a chance of overtaking the Belarusian despite dominating the major events in the second half of the year.
Azarenka needs only two wins in the elite, eight-player WTA Championships in Istanbul to end 2012 as No. 1.
Williams and Azarenka have been drawn into the same round-robin group. Play starts Tuesday.
"I don't really care who I play, when I play, as long as I can play," Williams said. "I'm really happy to be here. I'm on the Red side with Victoria, it'll be good."
Angelique Kerber of Germany and Li Na of China complete the Red Group.
French Open champion and second-ranked Maria Sharapova of Russia headlines the White Group, with former Wimbledon champion and last year's winner in Istanbul, Petra Kvitova of the Czech Republic, Agnieszka Radwanska of Poland and Sara Errani of Italy completing the bracket.
Since losing to Williams in the U.S. Open final, the last of the year's four Grand Slam tournaments, Azarenka has won 13 straight matches and has held the No. 1 ranking for 34 weeks.
She won the Australian Open in January and five more titles this year.