Yamaha Motor Co. has extended its contract with seven-time motorcycling world champion Valentino Rossi through 2008, the company announced Thursday.

Rossi, who turns 28 this month, will ride as part of Yamaha's Official Factory Team for another two seasons, Yamaha said in a statement.

Rossi has won two MotoGP World Championship titles and 25 Grand Prix since joining the team in 2004, it said.