Dutch cyclist Niki Terpstra suffered multiple injuries in a training crash in the Netherlands on Tuesday and was helicoptered to hospital, his wife said.
Terpstra, of the French Total-Direct Energy team, is a multiple classics winner.
He crashed while training near Lelystad in central Netherlands.
The rider's wife, Ramona Terpstra, confirmed Terpstra's fall in a tweet.
"Unfortunately the bad news is true. Niki crashed hard today during a bike workout."
"He's in the hospital and will have to stay here for a few more days. He is not in mortal danger but will need time to recover," she said.
Terpstra was training with some friends behind a moped when they had to swerve to avoid hitting some geese, public broadcaster NOS reported.
"Terpstra hit a rock and then crashed hard," NOS said.
He is reported to have suffered a collapsed lung, a concussion and to have broken ribs and a collarbone.
The 36-year-old has won the cobbled classics Paris-Roubaix and the Tour of Flanders.
It's not the first time he has suffered a bad fall.
Last year he suffered a heavy concussion when crashing in the Tour of Flanders only to then fracture a shoulder blade after crashing in the Tour de France, forcing him to abandon the race.