Britain’s Cal Crutchlow missed Sunday’s season-opening Spanish MotoGP after crashing during the warm-up in Jerez.
Crutchlow, who had qualified sixth, suffered concussion and neck trauma after taking a heavy tumble.
The 34-year-old LCR Honda rider, who will be leaving the team at the end of the season, got to his feet after the crash.
He attended the medical centre at the track but after further checks at hospital, was declared unfit to race.
The only full-time Briton in the sport will now hope to be fit for next weekend’s Andalucia Grand Prix at the same venue.
On Friday, Crutchlow told BBC Sport that MotoGP riders “cannot afford” injuries in the condensed season.