The 1990–91 European Cup was the 36th season of the European Cup, a tournament for men's football clubs in nations affiliated to the Union of European Football Associations (UEFA). It was won for the first time by Red Star Belgrade on penalties in the final against Marseille; both were first-time finalists. This was only the second time that an Eastern European side had won the competition, after Steaua București of Romania in 1986. It was also the last tournament to be solely knock-out based, with a group stage added for the next season. Red Star won the tournament as the only Yugoslavian club shortly before the breakup of Yugoslavia. This was also the last season to feature a team from East Germany, since the East and its West counterpart reunified in October 1990. Although 1990–91 marked the return of English clubs to the Cup Winners' Cup and UEFA Cup, after a five-year ban resulting from the Heysel Stadium disaster, Liverpool had been banned for an additional year, so could not participate in the European Cup as English champions. Ajax, the Dutch champions, were not allowed to participate in a European Cup competition because of the poor behaviour of their fans during a game the previous season, so their spot in the qualification was simply vacated, giving the two-time defending champions Milan a first-round bye. Milan were eliminated by Marseille in the quarter-finals after the second leg had been awarded as a 3–0 win for Marseille when the eventual runners-up were leading 1–0, and 2–1 on aggregate, in injury time, when the floodlights failed. Milan refused to play on when floodlights were fixed and were banned, giving Marseille a 3–0 automatic win. Teams A total of 31 teams participated in the competition. Notes First round |} First leg Second leg Bayern Munich won 7–2 on aggregate. Rangers won 10–0 on aggregate. Real Madrid won 10–1 on aggregate. CSKA Sofia won 3–1 on aggregate. Dinamo București won 5–1 on aggregate. Porto won 13–1 on aggregate. Red Star Belgrade won 5–2 on aggregate. Dynamo Dresden won 6–1 on aggregate. Malmö FF won 5–4 on aggregate. Napoli won 5–0 on aggregate. Spartak Moscow won 4–0 on aggregate. Swarovski Tirol won 7–1 on aggregate. Club Brugge won 3–1 on aggregate. Lech Poznań won 5–1 on aggregate. Marseille won 5–1 on aggregate. Second round |} First leg Second leg Bayern Munich won 7–0 on aggregate. Porto