NEW YORK (AP) ― Two days after playing her first match in two months, Venus Williams suddenly pulled out of the U.S. Open on Wednesday, revealing she was recently diagnosed with Sjogren’s syndrome, an autoimmune disease that can cause joint pain.

The 31-year-old American has won seven Grand Slam titles, including at Flushing Meadows in 2000 and 2001.

“I enjoyed playing my first match here and wish I could continue but right now I am unable to,” Williams said in a statement released by the tournament. “I am thankful I finally have a diagnosis and am now focused on getting better and returning to the court soon.”

She was supposed to face 22nd-seeded Sabine Lisicki in the second round Wednesday.

Williams cited a virus when withdrawing from hard-court tuneup tournaments since losing in the fourth round at Wimbledon in late June.

She returned to action Monday, beating Vesna Dolonts 6-4, 6-3 in the first round in New York, and then said: “No one is more in one-match-at-a-time mode than me now at this tournament. It will just be one match at a time, for sure.”

According to the Sjogren’s Syndrome Foundation website, the disease is a chronic autoimmune illness in which people’s white blood cells attack their moisture-producing glands. Common symptoms include dry eyes and dry mouth. As many as 4 million Americans have the disease.

In rare cases, it can cause arthritis and joint pain, said Dr. John Fitzgerald, director of clinical rheumatology at UCLA. Fitzgerald is not involved in treating Williams and does not know her symptoms or medical history. But, he said, if Williams has the typical symptoms, “it does not seem life-threatening or career-ending.”

Sharapova cruises

NEW YORK (AP) ― Maria Sharapova had nowhere near as tough a time with her second-round match in the U.S. Open as she did with her first.

The third-seeded Russian beat Anastasia Yakimova 6-1, 6-1 on Wednesday night in 70 minutes ― a far cry from the more than 2 1/2 hours she needed in a three-set win over Heather Watson in her opener two days before.

After a bit of a slow start, Sharapova turned it into a mismatch. She had 28 winners to two for her opponent. She won 59 points to 32 for Yakimova and saved all five break points against her.