Kim Clijsters has pulled out of next month's Indian Wells WTA tournament in California because of an injured left ankle, the Belgian former world number one said on Tuesday.
The elite March 5-18 event in the California desert, which attracts most of the leading players in the world, would have marked Clijsters's third tournament of the year.
"I'm very disappointed," Clijsters said in a statement. "Indian Wells has been a very special tournament for me, winning in 2003 and again in 2005 when I returned from injury.
"I have great memories of Indian Wells and have always enjoyed the fan support there. I wish the tournament a great success this year."
As defending champion, she reached the semifinals of last month's Australian Open where she was beaten 6-4 1-6 6-3 by Victoria Azarenka of Belarus.
Clijsters, a four-times grand slam singles champion, has confirmed 2012 will be her last on the WTA tour and she has spoken longingly of winning a medal at the London Olympics.
The 28-year-old, whose world ranking has slipped to 30th, has already retired once, married, become a mother and notched up 41 tour wins.