Venus Williams quit the U.S. Open on Wednesday, revealing that she was suffering from a chronic illness that could threaten her future in the sport.
After a week when the last grand slam of the year was threatened by an earthquake then a hurricane, this was perhaps the biggest shock of all.
The two-time U.S. Open champion told officials she was withdrawing from the tournament less than an hour before she was due to play Germany's Sabine Lisicki in the second round.
Then she dropped the bombshell, revealing for the first time exactly what had kept her off the courts for months.
"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 people 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.
The American 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 great perennial hope, made a bright start to his campaign while Argentina's Juan Martin Del Potro made a successful return two years after his stunning title success.
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 Robin Soderling, seeded sixth, 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 Andy 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.
On Wednesday, he finally made it back 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 favourite tournament," Del Potro said. "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 U.S. may eventually find a successor to the Williams sisters.
Russia's Vera Zvonareva, last year's runner-up and the second seed this time around, was never in any real danger of joining the casualty list even though she had a tough workout against Kateryna Bondarenko of Ukraine before triumphing 7-5 3-6 6-3.
There were five American winners among the men, including former champion Andy Roddick, but there was an upset when the Bryan brothers Mike and Bob were beaten by Ivo Karlovic and Frank, marking the first time in a decade the twins had been beaten in the opening round at a grand slam.