Colin Edwards is to undergo surgery after breaking his collarbone in second practice for the Catalan MotoGP.
The Monster Yamaha Tech 3 rider, who hasn't missed a race since his 2003 MotoGP debut, had been sixth fastest in the morning session, but was caught out by the drying afternoon track.
Edwards had completed one run on slick rubber when he switched bikes and was an out-lap when he crashed at Turn 5.
The Texan landed heavily and was immediately attended to by trackside marshals before being transferred to the Medical Centre, where further checks revealed he'd suffered a broken right collarbone.
Edwards was later taken to the Dexeus Institute Hospital in Barcelona where he will undergo surgery performed by Dr Xavier Mir, who has previously treated Dani Pedrosa and Jorge Lorenzo.
“Unfortunately Colin has broken his right collarbone and this is a big shame for him and for the Monster Yamaha Tech 3 Team because we were confident he was going to be very strong and competitive this weekend," said team manager Herve Poncharal.
"Colin has been superb so far this season and he has shown that even when the competition is probably stronger than ever in MotoGP, he is still one of the fastest out there. It looks like he paid a heavy price for a very small mistake. He landed heavily on his shoulder and it was clear from the TV pictures that he was in a lot of pain.
"He will have an operation tonight, so we should have a clearer idea of how long the recovery process will be later this weekend. The important thing now is that he rests and recovers as quickly as he possibly can. We wish him a fast recovery and hope that it is not too long before we see him back in the garage.”
Team-mate Cal Crutchlow added: "I'm really sad that Colin has got injured. He's been riding brilliantly all season and everybody at Monster Yamaha Tech 3 wishes him a speedy recovery.”
Edwards has finished a best of sixth this season, but was denied a twelfth MotoGP podium when his M1 broke down on the last lap in round two, at Jerez.
With Pedrosa also sidelined due to a broken collarbone, sustained last time out at Le Mans, the MotoGP field has been reduced to just 15 riders.
Both Edwards and Pedrosa are also likely to miss next weekend's British Grand Prix.