During the 1989–90 Season, Costacurta won his second consecutive European Cup with Milan, defeating Benfica 1–0 in the final in Vienna, and starting the play which led to Frank Rijkaard's match-winning goal. He also featured in Milan's Intercontinental Cup win in Tokyo over Atlético Nacional, and in the European Supercup victory over Johan Cruyff's Barcelona. Costacurta also scored his first goal in Serie A during that season, in a 3–1 away defeat to Milanese rivals Internazionale in the "Derby della Madonnina". Milan would also reach the Coppa Italia final that season. In Sacchi's final season at the club, Costacurta would become a starting centreback alongside Franco Baresi, as well as full-backs Mauro Tassotti and Paolo Maldini, in Sacchi's four-man defensive line, which is regarded as one of the greatest defences of all-time. Costacurta would make 25 appearances in Serie A that season, and he would also win his second consecutive Intercontinental Cup and European Super Cup trophies.