Nine-time world champion Valentino Rossi suffered a broken right tibia in a vicious practice crash today at Mugello’s fourth round of the MotoGP World Championship, undergoing surgery in Italy on Saturday afternoon.

Rossi’s injury marks the first major incident that the Italian has suffered in his illustrious career, this weekend’s GP set to be the first round that Rossi has missed since his grand prix career commenced in 1996. His successive 230 race streak is a record in grand prix racing.

The defending world champion fell at Turn 13, the top of the fast chicane at Mugello, as his Fiat Yamaha YZR-M1 in a nasty high-side crash.

Rossi was stretchered from the track and taken directly to the medical centre, where the 31-year-old underwent X-rays which confirmed a displaced and exposed fracture of his right tibia.

“It’s an injury more serious than we thought, because it’s an exposed fracture with the bone protruding from the skin,” doctor Claudio Macchiagodena of the Clinica Mobile told the official MotoGP website.

“We have reduced the fracture, which fortunately has not affected any blood vessels or nerves.”

Regarding the time that Rossi could be forced out of action, doctors say it’s too early to say, however Rossi’s demise effectively puts teammate Jorge Lorenzo in the box seat for the crown in 2010.

Speculation at the circuit indicates he could be out for at least four races, with MotoGP regulations stating that a team can compete for two rounds with only one rider, however after that then they are required to bring in a replacement for proceeding rounds.

“It is serious, it could be a couple of months, but it is too early to say just yet,” doctor Macchiagodena continued. “He remained calm, but having seen the images he could already see it was a nasty fall.”

Rossi was then flown by helicopter to the Careggi Hospital in Florence for a further medical examination, and was moved to the orthopaedic trauma centre afterwards, which is close to the hospital. He was set to have an operation in the afternoon.

Spanish Repsol Honda rider Dani Pedrosa later scored pole position for the round ahead of Lorenzo and Australian Ducati Marlboro rider Casey Stoner. Stay tuned for a full qualifying report.

Click here for a free video from Dorna displaying the high-speed fall on the Mugello circuit’s surveillance cameras.