World number three Maria Sharapova has withdrawn from the season-ending WTA Championship in Istanbul with a shoulder injury.

The 26-year-old Russian was recently forced to pull out of the US Open with the same problem.

"I am very disappointed I will not be able to play in the TEB BNP Paribas WTA Championship this year," Sky Sports News quotes Sharapova as saying.

"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."

The WTA Championship gets underway on October 21.