 After Kaká left the club in the summer 2009 transfer window, Borriello chose to switch to shirt number 22, which he had worn at Genoa.After a disappointing first season, Borriello scored his first ever brace for the "Rossoneri" in their 2–0 win over Parma on 1 November 2009.On 25 November, Borriello scored his first UEFA Champions League goal in a match against Marseille which finished 1–1.