Ducati's Marc Marquez suffered a collarbone injury as a result of a collision with Marco Bezzecchi at the Indonesia Grand Prix on Sunday, his team said.
In the first lap of the race, Bezzecchi collided with the rear of Marquez's Ducati and the pair both hurtled into the gravel at high speed, with Marquez appearing to be in significant discomfort after tumbling head over heels.
The Spaniard, who won his seventh MotoGP championship at last week's Japanese Grand Prix, was hunched over on the side of the track for a couple of minutes before staggering to his feet and lurching away while clutching his shoulder.
He was later seen with his arm in a sling, with members of Ducati team saying on the race's broadcast that there was evidence of a fracture after initial scans.
"As a result of today's crash at Indonesian GP, Marc Marquez has suffered an injury to his right collarbone," Ducati said in a statement on social media.
"The Spanish rider will travel tonight to Madrid (Spain) for further medical tests and to decide on the treatment to follow."
The injury was on the shoulder of the arm Marquez fractured in the 2020 July season-opening Spanish Grand Prix in Jerez, which ruled him out for an extended period and required several surgeries.
"Not the best way to celebrate the championship," Marquez told reporters after the race.
"In the end, Marco Bezzecchi already came to me and said sorry. This happens. It's something that sometimes I will do, sometimes somebody else will do, but it was not on purpose. So, Marco accepted it was his fault.
"We will fly to Madrid and try to understand with the doctors exactly what is wrong and try to come back as soon as possible."
In a separate statement, Aprilia confirmed that Bezzecchi would also be taken to hospital to undergo a more comprehensive examination following the crash.
Marquez's Ducati teammate Francesco Bagnaia, Joan Mir (Honda HRC) and Enea Bastianini (Red Bull KTM Tech3) also crashed out of Sunday's race, won by rookie Fermin Aldeguer.