Two-time defending U.S. Open champion Kim Clijsters will not play this year's tournament, the USTA confirmed to TENNIS.com.

Since tearing a ligament in her ankle while dancing at her cousin's wedding in early April, Clijsters has only managed to play five matches. She returned to play last week in Toronto and suffered a partial tear of her left abdominal muscle in her match against Zheng Jie, which Clijsters retired leading 6-3, 1-2. Clijsters has not won a title since winning her fourth Grand Slam at the 2011 Australian Open.

In a statement released by the USTA, Clijsters said:

“Unfortunately, I will not be able to defend my U.S. Open title this year because of a stomach muscle injury (left rectus abdominus strain). Two weeks of rehab was not enough to heal this injury. Obviously I’m very disappointed. I trained very hard this summer and felt in a good shape to play the U.S. Open.”

“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 in the same injury, and therefore I have also no other possibility than to withdrawal from the tournaments in Tokyo and Beijing.”

In her blog, the 28-year-old Clijsters added that she does plan on playing in 2012:

"I'll be there again next year!," she wrote. "The Diamond Games on December 8 at the Sportpaleis in Antwerp are the first test, and then in early January, Australia...In my head I focus now on 2012, the Olympics and who knows, if I'm spared from injuries maybe one last U.S. Open."