Originally a Milan youth squad product, Maldini also went on to play his entire club career with the Milan senior side. He won the Coppa Italia Primavera with the Milan Youth side during the 1984–85 season, and he made his league debut for Milan under manager Nils Liedholm during the same season on 20 January 1985, replacing the injured Sergio Battistini in a match against Udinese at age 16. It was his only league appearance of the campaign, but he was immediately made a member of the starting eleven the following season, at age 17, at right-back, being handed the number 3 shirt, which had previously also belonged to his father, Cesare. He was later switched to his more iconic position of left-back due to his ability with his left foot. Maldini also made his Coppa Italia debut in 1985, on 21 August, while his debut in European competition also came later that same year, on 18 September. He scored the first of his 29 goals in Serie A on 4 January 1987 in a 1–0 win against Como.