Valentino Rossi will return to Yamaha on two - year deal from start of 2013 season . Two - time world champion has retired since leaving to join Ducati in 2011 . MotoGP series champion Jorge Lorenzo welcomes the return of his former teammate . Lorenzo says Rossi will be motivated by the prospect of renewing their rivalry .
Valentino Rossi will return to Yamaha on two-year deal from start of 2013 season . Seven-time world champion has struggled since leaving to join Ducati in 2011 . MotoGP series leader Jorge Lorenzo welcomes the return of his former teammate . Spaniard says Rossi will be motivated by the prospect of renewing their rivalry .