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Franco Baresi, the legendary Italian defender, was Costacurta's renowned defensive partner. Together, they formed an impenetrable defensive duo for AC Milan and the Italian national team. Baresi, known for his exceptional leadership, positional awareness, and tackling skills, complemented Costacurta's speed, agility, and aerial prowess. Their partnership was instrumental in Milan's numerous domestic and international triumphs, including five European Cups and six Serie A titles.