Venus Williams follows through on a backhand retrurn during her first-round… (Charles Krupa / Associated…)
Reporting from New York -- Venus Williams isn't ready to walk away from tennis, but she had to Wednesday, leaving the U.S. Open with her head down.
Williams, 31, pulled out of her second-round match against 22nd-seeded Sabine Lisicki, a big-serving German who is a decade younger than Venus.
In a statement, Williams said she had an autoimmune illness called Sjogren's syndrome. The illness, Williams said, "affects my energy level and causes fatigue and joint pain."
Carlos Fleming, Williams' longtime agent, looked downcast outside the locker room after the announcement.
"I just hope she's OK," he said. "I hope she'll get healthy again and be fine."
Williams hadn't played since losing in the fourth round at Wimbledon in July and was unseeded at the U.S. Open for the first time since she debuted in 1997 and made it to the final.
But after winning her first-round match Monday, Williams spoke with delight about being on the court and hope about her future.
"I'd be at a $50,000 challenger where I live at," she said. "I'd be at any tournament I could play. I just want to play tennis. It doesn't matter what the tournament is, I just want to play."
Less than two days later, though, there are questions about whether Williams will be back in the sport in which she has won seven major titles, including two U.S. Opens.
Dr. Eric Matteson, chairman of the rheumatology department at the Mayo Clinic, said Sjogren's causes fatigue but can do much more. The most common symptoms are extreme dryness of the eyes and mouth, but it can affect other organs.
"It can cause joint pain and joint swelling," he said. "It can cause nerve disease in the hands and legs and even affect the central nervous system and cause kidney disease and lung disease."
Dr. John FitzGerald, an assistant clinical professor of rheumatology at UCLA, said most Sjogren's patients have an inflammatory phase and a chronic phase. FitzGerald said it's possible that if Williams has a mild case, she might be ready and able to play at the Australian Open in January.
Matteson said the future for an elite athlete would be problematic if the case is severe.
"An athlete might see a very dramatic drop in his or her level of performance, even once the disease is under control," Matteson said.
Treatment also varies depending on the severity. It can be as simple as eye drops to control dry eyes, Matteson said. It can be more complicated though. FitzGerald said some patients need treatment with corticosteroids such as prednisone to tame inflammation, and Matteson said some patients need chemotherapy depending on organ involvement.
Matteson is a tennis fan. He said he received a text message from his wife Wednesday when Williams' news became public.
"I'd love to see her back at the top of her game," Matteson said. "But I don't think it's a guarantee."
Andy Roddick, who turned 29 this week and who has known Venus and her sister Serena for almost 20 years, said he was worried about Venus.
"I do know one thing," Roddick said after outlasting 33-year-old American Michael Russell, 6-2, 6-4, 4-6, 7-5, in a first-round match Wednesday night, "I'm very concerned. If Venus isn't playing at the U.S. Open, it's got to be something. She didn't withdraw because she's sneezing too much."
Two unheralded young Americans earned major upset victories and moved into the third round. Christina McHale, 19, picked up a 7-6 (2), 6-2 win against eighth-seeded Frenchwoman Marion Bartoli, who beat Serena Williams at Wimbledon, and 21-year-old Irina Falconi, ranked 78th in the world, eliminated 14th-seeded Dominika Cibulkova, 6-2, 3-6, 7-5.