From MotoGP files

Valentino Rossi's team manager Davide Brivio believes that his star driver could walk out on Fiat Yamaha at the end of this year if they do not improve next season.

Rossi had a difficult 2007 season and he was no match for Casey Stoner. The Italian finished only third in the MotoGP riders' championship, behind Stoner (Ducati) and Dani Pedrosa (Honda).

"Valentino must decide what to do in 2009," Brivio said in an interview with Gazzetta dello Sport. "That's why 2008 will be an extremely important year. For us at Yamaha, but also for the entire motorcycling world."

Brivio also believes that as well as facing the continued threat from reigning champions Ducati in 2008, rivals Honda will join the title battle.

Fiat Yamaha are unveiling their new bike at the Giovanni Agnelli Auditorium in Turin today.