Reigning seven time MotoGP world champion Valentino Rossi has been ruled out of the remainder of his home Italian MotoGP after being diagnosed with a fractured right shinbone.

"Valentino Rossi has suffered a displaced and exposed fracture of his right tibia after crashing in practice for the Italian Grand Prix in Mugello this morning," said a Fiat Yamaha statement.

"The reigning World Champion crashed his Fiat Yamaha M1 at turn thirteen, the fast chicane at the top of the hill, and was taken immediately to the circuit Medical Centre for x-rays.

"Further information will be made public as soon as a more detailed examination has been completed."

With three races this month - and six races between now and July 25, when the summer break begins - the injury is a monumental blow to Rossi's hopes of winning a tenth world title in 2010.

The #46, who immediately grabbed his lower right leg after the incident, has never previously missed a race, since his 1996 grand prix debut in the 125cc class.