On 15 January 2009, A.C. Milan in Italy acquired Mattioni on loan, with the "Rossoneri" having an option to buy the player at the end of the campaign. He played his first match in a 2–2 friendly draw to Rangers, but failed to make an impact due to leg injuries, his Serie A input consisting of two minutes in a 2–0 away victory over Calcio Catania on 3 May.