Venus Williams pulls out of U.S. Open

The U.S. Open witnessed a major shock without a ball being struck in anger on Wednesday when Venus Williams quit the tournament after revealing she was suffering from an illness that could threaten her tennis future.

After a buildup to the last grand slam of the year in which the event was threatened by an earthquake then a hurricane, the American's revelation was perhaps the most earth-shattering news of the week.

The two-time champion told officials of her withdrawal from the tournament less than an hour before she was due to face Germany's Sabine Lisicki in the second round.

Then she dropped the bombshell, revealing for the first time exactly what had kept her recent playing time down to a bare minimum.

"I have recently been diagnosed with Sjogren's Syndrome," she said in a statement. "(I) wish I could continue but right now I am unable to."

The disease drains victims of their energy and causes joint pain. For a professional tennis player, that spells trouble but Williams said she had no thoughts of retiring.

"I am thankful I finally have a diagnosis and am now focused on getting better and returning to the court soon," she said.

At 31, speculation about her future in the sport is sure to intensify but fellow American Andy Roddick, who has been friends with the Williams sisters since they were children, said her health was the most important issue.

"I do know one thing. I'm very concerned, because if Venus isn't playing at the U.S. Open, it's got to be something," he said.

"She didn't withdraw because she's sneezing too much."

Williams was not the only high-profile casualty at Flushing Meadows on Wednesday but her illness did overshadow most of the on-court action.