Continuing back problems have prompted Dinara Safina to end her season after a first-round loss to Vera Zvonareva in Beijing.
"My back injury is acting up again and I've decided not to play any more tournaments the rest of the season," said Safina on her website. "It has been the worst year of my career mainly because of my injury that has kept me away from several tournaments and kept me from playing my game of tennis."
The injury caused Safina to miss three months after the Australian Open, and she has struggling since returning at the beginning of the clay season.