Alex Rins suffers broken leg in Sprint race accident, needs multiple surgeries
The incident was not broadcast, but the COTA winner is thought to have fallen at the fast Arrabiata 1 corner (on lap 4 of 11) and to have sustained the injuries when he tumbled awkwardly in the gravel.
After initial treatment at the medical centre, the LCR Honda rider was transported to a hospital in nearby Florence.
The team report that Rins will 'undergo a first surgery this evening at the Careggi University Hospital (Florence), where doctors will attach an external fixator to stabilize his right leg and reduce swelling.
'He will remain under observation, and once cleared, he will return to Spain to undergo a final surgery.'
The injuries are sure to rule Rins out of the following Sachsenring and Assen rounds, which follow Mugello on consecutive weekends.
The MotoGP summer break then runs until Silverstone at the start of August.
Third fastest on Friday, Rins had qualified in ninth place and was twelfth when he fell.