NEW YORK (AP) — Venus Williams says she’s eager to return to action after withdrawing from the U.S. Open because of an immune system disease.

Williams took to Twitter on Sunday, writing: “Thank you everyone for all your well wishes! It’s good to have support! Looking forward to getting better and back on tour!”

When the seven-time Grand Slam singles champion pulled out of the tournament before her second-round match Wednesday, Williams revealed that she’s been diagnosed with Sjogren’s syndrome, which can cause fatigue and joint pain.

She tweeted Sunday: “Thank you 4 sharing all your sjogrens & auto immune stories w/me. Feels good to know I’m not alone! feel better to you and your loved ones!”

Copyright 2011 The Associated Press.