AC Milan 1988–1990 — Sacchi's Double European Champions

Arrigo Sacchi's AC Milan claimed back-to-back European Cups in 1989 and 1990, the Serie A title in 1988, and two Intercontinental Cups, making them the most dominant team of their era. Their defensive record is staggering: they conceded just 14 goals in 18 European Cup matches across both campaigns. The Dutch trio of Gullit, Van Basten, and Rijkaard—Van Basten scored 33 Serie A goals in 30 games in 1988–89—formed the attacking spine, while Baresi, Costacurta, Maldini, and Tassotti anchored the most tactically coherent back four in football history. They went 58 competitive matches unbeaten between 1991 and 1993, outperforming #4 AC Milan 1993–94's single-season unbeaten run in terms of duration.