Denmark's Caroline Wozniacki is certain to end the year as the world No. 1 but her chances of winning the WTA Championships took a blow Wednesday.
Wozniacki was guaranteed the No. 1 ranking in women's tennis after Russian Maria Sharapova withdrew from the season-ending event in Istanbul with an ankle injury.
Sharapova, who began the day as the only player still able to topple Wozniacki from the top spot, quit after losing 7-6 6-4 to China's Li Na, her second round-robin defeat at the tournament.
Wozniacki, 21, then lost 6-2 4-6 6-3 to Russia Vera Zvonareva. The defeat was immaterial as far as the rankings go but, with one win and one loss in the Red Group, Wozniacki could miss out on the semifinals even if she beats Wimbledon champion Petra Kvitova Thursday.
Wozniacki, who has won six titles in 2011, was not going to let defeat spoil her day.
"Only very few players have finished a year as No. 1 and to do it two years in a row is very special," she said. "I'm only in the beginning of my career and to have achieved so much already, it's a dream come true."