The defending champion Kim Clijsters has pulled out of the U.S. Tennis Open due to a stomach muscle injury.
The former world number one suffered a partial tear of her left stomach muscle in Toronto earlier this month in what had been her first appearance since picking up a foot injury in June.
The four-times grand slam winner also says she will also have to skip tournaments in Japan and China scheduled for September and October.
Clijsters also had to miss this year's Wimbledon Championships and she has suffered a series of injuries since she won the Australian Open in January.
In fact, the world number three has played only five matches over the past five months, during which she has nursed shoulder, wrist, ankle and foot injuries before suffering her latest setback.
The Belgian retired in May 2007 before marrying basketball player Brian Lynch and giving birth to a daughter.
She returned to the WTA tour in 2009 winning that year's U.S. Open just weeks into her comeback.