MotoGP legend Valentino Rossi has suffered a broken leg in a motocross training accident.
Rossi sustained the injury to both the tibia and fibula of the right leg that he previously broke in his high-speed practice crash at Mugello in 2010.
In a statement, Rossi's Yamaha team said: "Following an enduro training accident on Thursday, August 31st, Movistar Yamaha MotoGP star Valentino Rossi was diagnosed with displaced fractures of the tibia and fibula of his right leg.
"The 38-year-old Italian rider will undergo surgery as soon as possible."
Rossi's father Graziano told ANSA: "Valentino is not optimistic.
"To do the radiograph they had to cut the boot, and Valentino told me he feels very bad."
The nine-time world champion is currently fourth in the MotoGP standings, having recently finished third at Silverstone.
Autosport has produced a standalone special magazine to celebrate our 70th birthday. All current print subscribers will receive a copy for free. To order your copy of the 196-page Autosport 70th Anniversary issue, please go to: autosport.com/autosport70th