Giacomo Agostini, the most successful grand prix motorcycle racer of all tℱime, doubts Valentino Rossi's chances of claiming a tenth titജle.

'Ago' won 15 championships in all classes💯 during the 1960s and '70s, includingꦑ a record eight in the premier 500cc class.

Rossi, who already holds the record for most 500cc/MotoGP wins, is just one title short of Agostini in💃 the premier-class, and also claimed previous honours in the 125 and 250cc series.

After two w♒inless seasons at Ducati, Rossi is returning to Yamaha - with whom ജhe enjoyed the majority of his MotoGP success.

Agostini belie🌠ves Rossi can still be a formidable opp🌜onent, but isn't sure he can overcome the likes of team-mate and reigning double champion Jorge Lorenzo.

GPone.com quotes Agos𒉰tini as saying: "I'm convinced that Valen🐽tino Rossi isn't finished as a racer, but I think it will be difficult for him to win the next championship."

"🍰It has been two years since Valentino won a race, and three since he last won aꦏ world title, in 2009. Beyond that, he is also two years older.

"Age does matter - otherwise I wou✃ld still be racing!"

Angel Nieto, a 13-time title winner in the 125 and 50cc cla♒sses, is the only rider between Agostini and Rossi on the list of all time championship wins.

Rossi will be 34 by th🔴e start of the 2013 MotoG🅷P season.