| Venus Williams has been diagnosed with Sjogren's Syndrome which drains sufferers of their energy [GALLO/GETTY]
The US 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."
"I do know one thing. I'm very concerned, because if Venus isn't playing at the US Open, it's got to be something"
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 US Open, it's got to be something," he said.
Williams was not the only high-profile casualty at Flushing Meadows on Wednesday but her illness did overshadow most of the on-court action.
Andy Murray, Britain's perennial major hope, made a bright start to his campaign while Argentina's Juan Martin Del Potro enjoyed a successful return to Flushing Meadows two years after his stunning title success.
However, three seeded women made early exits at the hands of lower-ranked players.
Marion Bartoli, Dominika Cibulkova and Yanina Wickmayer all departed while the only male seed to lose was Nicolas Almagro of Spain, although sixth seed Robin Soderling pulled out because of injury.
The Swede had been regarded as one of the few players able to challenge the big four of Roger Federer, Rafa Nadal, Novak Djokovic and Murray, but threw in the towel before his first round match.
Murray launched his campaign with a 7-6 6-2 6-3 victory over Somdev Devvarman of India. The Scotsman played below his best but still had plenty in reserve.
"It's all about just winning," Murray said.
"That's all that matters at the end of the day."
Del Potro upset Federer to win the men's title two years ago but was unable to defend it because of a wrist injury that sidelined him for nearly nine months.
He finally returned to the scene of his greatest triumph and the towering Argentine was in a hurry to make up for lost time, crushing Italy's Filippo Volandri 6-3 6-1 6-1.
"It's my favorite tournament," Del Potro said.
| Brit Murray cruises into the next round after beating Devvarman of India [GALLO/GETTY]
"I'm really happy to get the opportunity to play here again."
The women's draw, already depleted by the absence of Kim Clijsters and the early defeats of Petra Kvitova and Li Na, lost Bartoli to American Christina McHale and Cilbulkova to Irina Falconi, another American, giving rise to hope that the US may eventually find a successor to the Williams sisters.
Russia's Vera Zvonareva, last year's runner-up, was never in any real danger of joining the casualty list even though the second seed had a tough workout against Ukraine's Kateryna Bondarenko before triumphing 7-5 3-6 6-3.
Third seed Maria Sharapova concluded the day with a late night 6-1 6-1 romp past Anastasiya Yakimova of Belarus in a match that started in August and finished in September because it trickled past midnight.
"A big part of our sport is adjusting to whatever comes our way, whether it's the time of a match or opponents or conditions on the court," Sharapova said.
"It's one of the toughest things in our sport: sometimes you never know exactly what you're going to get."