Franco Morbidelli is to undergo surgery for the knee injury that has ruled him out of this weekend's Assen round.

The Petronas Yamaha rider first injured his left knee during training in May, the problem being thrown into the spotlight when he collapsed during a bike swap practice at Le Mans.

While the Italian has been able to continue riding since, another training accident caused further damage to his meniscus and anterior cruciate ligament, forcing him to miss the Dutch event.

On Thursday evening, Petronas Yamaha announced that, 'in light of the results highlighted by the tests carried out in these days, Franco Morbidelli has decided to undergo surgery tomorrow, Friday, June 25.'

While MotoGP has a five-week summer break after Assen, a full recovery from knee ligament surgery usually takes months rather than weeks.

American Garrett Gerloff is currently replacing title runner-up Morbidelli, who has taken one podium so far this season on the older A-Spec Yamaha.