Maria Sharapova on Monday withdrew from the season-ending WTA Championships in Istanbul because of a right shoulder injury that has dogged her since before the US Open, The Women's Tennis Association announced.

The 26-year-old Russian - currently No 3 in the world - had had to withdraw from the US Open on the eve of the tournament because of the injury and, owing to a previous hip problem, she has played just one match since a second-round exit at Wimbledon in June.

"I am very disappointed that I will not be able to play in the WTA Championships this year," said Sharapova, whose turbulent season has also been marked by her splitting with Jimmy Connors after just three weeks as her coach.

"The fans in Istanbul have welcomed us each year with such intense passion and warmth. I will sincerely miss the energy and excitement they brought to the year-end tournament.

"I want to thank Istanbul for being a tremendous host and hope to play in Turkey some time in the future."

While the popular Russian won't be there, the WTA also announced three more players had qualified for the tournament, which takes place from Oct 22-27.

The trio is Czech Republic's Petra Kvitova, winner of two titles this season, Italy's Sara Errani, who has won one of her four finals this campaign, and Serbia's Jelena Jankovic, who ended a three-year title drought when she won in Bogota, Colombia.

They join earlier qualifiers Serena Williams, Victoria Azarenka, Agnieszka Radwanska and Chinese star Li Na.

The WTA Championships features the top eight singles players and the top four doubles pairings competing for a record $6 million in prize money and will be hosted in Istanbul for a third successive year.

- Agence France-Presse