Swiss Moto3 rider Jason Dupasquier has died after a crash in Saturday's qualifying session of the Italian Grand Prix at the Mugello Circuit.
Dupasquier was airlifted to a hospital in Florence after a crash at turn nine involving three bikes.
He was treated by medical staff for more than 30 minutes on the track as the session was red-flagged.
"Despite the best efforts of circuit medical staff and all those subsequently attending to the Swiss rider, the hospital has announced that Dupasquier has sadly succumbed to his injuries," MotoGP said in a statement.
"On behalf of the entire MotoGP family, we send our love to his team, his family and loved ones. You will be sorely missed, Jason. Ride in peace."
World championship leader Fabio Quartararo of Yamaha had dedicated his record lap in Saturday's qualifying to Dupasquier after the crash.
The scheduled races went ahead on Sunday, with MotoGP saying Dupasquier remains "at the forefront of our minds" as condolences poured in from teams.
But his team, Prustel GP, announced they would not be taking part in Sunday's race.
Dupasquier, 19, was in his second season in MotoGP's lightweight class and was in the the top 10 in the overall standings heading into the weekend.
"The entire community shares in this loss together," Ducati said.
"No words can express, but we send our warmest wishes to the motorcycling family in this difficult tragic moment."