Maria Sharapova has withdrawn from the season-ending WTA Championship as she continues to battle a shoulder injury.
The world No 3 has not played since she was beaten in the second round of the Western and Southern Open in Cincinnati in August.
And the problem which kept her out of the US Open last month will also sideline her in Istanbul.
"I am very disappointed I will not be able to play in the TEB BNP Paribas WTA Championship this year," Sharapova said.
"The fans in Istanbul have welcomed us each year with such intense passion and warmth. I will sincerely miss the energy and excitement they bring to the year-end tournament."
Sharapova's withdrawal leaves one place in the tournament up for grabs, and the rankings will decide who goes to Turkey along with Serena Williams, Victoria Azarenka, Agnieszka Radwanska, Li Na, Petra Kvitova, Sara Errani and Jelena Jankovic.