Felix Neureuther will miss the Winter Olympics after tearing the anterior cruciate ligament in his left knee.
The German skier was training for the giant slalom in Colorado when he crashed arriving late at a gate.
A scan later confirmed that Neureuther's season is over, ruling him out of the rest of the World Cup season and the Olympics in Pyeongchang, which start in February.
"After the knee felt unstable, I drove to the Vail hospital, where the doctors diagnosed the cruciate ligament tear in my left knee with an MRI scan, and of course, the injury is extreme, especially after the successful start of the Olympic season," he said.
"But I've had some setbacks in my career and I know how to deal with them, so I wish our team all the best for the season."
Neureuther has 13 career World Cup wins, with 11 of those coming in the slalom discipline - including in this month's season-opener in Levi.
The 33-year-old is to return to Germany in the coming days to undergo surgery.