New York: Former  U.S. Open champion Venus Williams withdrew from the last grand slam of  the year on Wednesday after revealing she is suffering from an  autoimmune disease.
The former world number one quit the  tournament before her second round match against Germany's Sabine  Lisicki and then released a statement explaining her health problems.
"I'm  really disappointed to have to withdraw from this year's U.S. Open,"  she said in the statement. "I have recently been diagnosed with  Sjogren's Syndrome, an autoimmune disease which is an ongoing medical  condition that affects my energy level and causes fatigue and joint  pain."Williams, who has been battling health problems for the  past year, retired from her third round match at the Australian Open  with a hip problem and did not play again until June.
The 31-year-old played only a handful of matches because of what she said was an "energy-sucking" mystery illness.
She  won her first round clash with Vesna Dolonts of Russia 6-4 6-3 on  Monday even though there were signs she was below her best.
"I  enjoyed playing my first match here and wish I could continue but right  now I am unable to," said Williams. "I am thankful I finally have a  diagnosis and am now focused on getting better and returning to the  court soon."
Williams has not won a grand slam singles title since 2008.
Speculation  about her future has intensified over the past few months but earlier  this week she confirmed she had no intentions of retiring.
