News Americas, FLUSHING, NY, Thurs. Sept. 1, 2011: A disease that affects energy level and causes fatigue and joint pain has forced former U.S. Open champion Venus Williams out of this year’s tourney.

Venus Williams announced the stunning withdrawal Wednesday, August 31st, after revealing she is suffering from an autoimmune disease called Sjogren’s Syndrome.

“I’m really disappointed to have to withdraw from this year’s U.S. Open,” she said in the statement after her second-round match against Germany’s Sabine Lisicki. “I am thankful I finally have a diagnosis and am now focused on getting better and returning to the court soon.”

Williams, 31, has been battling health problems for the past year and retired from her third-round match at the Australian Open with a hip problem and did not play again until June.

Sjogren’s Syndrome is a chronic disease where white blood cells attack moisture-producing glands. The most common symptoms are dry eyes and dry mouth but the illness can also cause dysfunction of other organs and body systems.