Jorge Lorenzo fractured his backbone and will miss the Dutch MotoGP race after a crash in practice on Friday.
The Repsol Honda rider, who also crashed at the Catalunya Grand Prix and in a post-race test in Barcelona, came flying off his bike at high speed at Turn 7 on the Assen track.
The incident kept 32-year-old Lorenzo, already complaining of chest and back pain, out of the second practice session as he underwent scans.
It was discovered Lorenzo had suffered a fractured vertebra and would not be fit to return for the remainder of the weekend, including Sunday's race.
"Jorge reported on the CT scan a fracture on the sixth thoracic vertebra, so they are still deciding how to proceed," doctor Michele Zasa said.
"He will most probably fly back to Barcelona where he has his own trusted neurosurgeon to check on him. He will probably also undergo further checks, specifally an MRI, but this is still a phase when they are deciding what to do.
"For sure, he's unfit, for the moment; there is this reported fracture on the sixth thoracic vertebra - no neurological signs, this is important to say. He moves everything and doesn't have any neurological signs.
"The helmet has external signs like scratches but he didn't lose consciousness, he was OK, not knocked out or concussed.
"So, the contusion was to the chest and the back."
Meanwhile, in the second free practice session, Maverick Vinales went fastest ahead of Fabio Quartararo in a reverse of the FP1 times.