UPDATE: MotoGP's Rossi fractures tibia and fibula during training

UPDATE: Valentino Rossi was diagnosed with displaced fractures of the tibia and fibula of his right leg, and the nine-time MotoGP champion will undergo surgery as soon as possible.

The 38-year-old was involved in an enduro accident during training close to his hometown Tavullia on Thursday. The Italian rider was taken to the Ospedale Civile di Urbino.

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Valentino Rossi is feared to have fractured his right tibia and fibula in an endurance motocross accident, with father Graziano telling Italian media "Valentino is not optimistic."

According to Italian media reports, Rossi is undergoing X-rays, but the injuries could be the same as those he suffered in the same leg in 2010 during the Italian Grand Prix.

Graziano Rossi told ANSA that in order to undergo tests, his son's boot had to be cut, and "Valentino told me he feels very bad."

Rossi, who currently sits fourth in points, could miss the next two rounds at Misano (Sept. 10) and Aragon (Sept. 24).

This would be the second major injury the nine-time MotoGP champion has suffered in out-of-race activities this year.

In May

, Rossi suffered mild thoracic and abdominal trauma but no fractures in a training accident at the Cross Club Cavallera in Mondavio, Italy. He was taken to a local Rimini hospital and released a short time later, and he was cleared for his home race at Mugello.