Maria Sharapova has withdrawn from the season-ending WTA Championships because of an injured right shoulder.
The WTA says the third-ranked Russian will miss the Oct. 22-27 tournament in Istanbul because of the injury, which has sidelined her for most of the second half of the year.
Sharapova thanked Istanbul for being a "tremendous host" and said she hopes to play in Turkey in the future.
The WTA says Petra Kvitova of the Czech Republic, Sara Errani of Italy and Jelena Jankovic of Serbia have qualified for the championships. They join a field that already includes Serena Williams, Victoria Azarenka, Agnieszka Radwanska and Li Na.
The tournament features the top eight singles players and top four doubles teams.