Italy's Marco Melandri injured his right leg in Friday's MotoGP practice session and will be unable to take part in Sunday's season-opening Grand Prix of Japan.
Melandri, the 2002 250cc champion, slid from his Yamaha YZR-M1 on a right-hand corner at the 5.8-kilometer (3.6 mile) Suzuka circuit.
Initial reports from the Suzuka circuit medical center indicate that Melandri has a fracture to his right femur and ankle.
The 20-year-old Melandri was fully conscious after the accident and said the bike made contact with him in the fall.
Melandri was set to make his MotoGP debut in Sunday's race.
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