Kim Clijsters became the first big name to pull out of the US Open due to the abdominal injury she suffered in Toronto.
The popular Belgian is a three-time champion in New York but injuries have sidelined her for much of this year after winning the Australian Open. She missed most of the clay-court season and Wimbledon with an ankle injury and on her return at last week's Canadian Masters she injured a stomach muscle during the warm-up for her opening match against Jie Zheng.
"Unfortunately, I will not be able to defend my US Open title this year," Clijsters said in an official statement. "Two weeks of rehab was not enough. Obviously I'm very disappointed. I trained very hard this summer and felt in a good shape to play."
"Now there is nothing else I can do than to rest and have treatment every day. If a gradual approach is not taken, I will relapse, and therefore I have also no other possibility than to withdraw from the tournaments in Tokyo and Beijing."
She will not return to action until the late autumn at the earliest and may miss the end of season WTA Championships.
In the past the 28 year old has hinted that she may retire for good after next year's London Olympics to continue her plans for starting a family. It will be interesting to see if those plans change, particularly if she does not win Wimbledon next summer.
