1983–84 S.L. Benfica season left the club in second, a point shy of the leader Porto, their next opponent. In the Clássico, Benfica beat his rival Porto and assumed first place. Later in the month, Benfica defeated Olympiacos in the second round of the European Cup, qualifying for the quarter-final. In November and December, Benfica won all their league matches, but lost the Supertaça Cândido de Oliveira to Porto. Benfica kept on winning in the Primeira Divisão in January, lapping the first part of league with a three-point lead. However they suffered a set-back in the Taça de Portugal, losing 2–1 in Estádio de
FC Porto in international football competitions name="1980/81"></ref><ref name="1982/83"></ref> In between, the club sailed into the 1981–82 Cup Winners' Cup quarter-finals, where they were beaten by the eventual runners-up Standard Liège.<ref name="1981/82"></ref> Porto lost the 1983 Portuguese Cup final to league champions Benfica, which allowed their participation in the 1983–84 Cup Winners' Cup as losing cup finalists. They eliminated Dinamo Zagreb, Rangers, and Shakhtar Donetsk to reach their first European semi-final.<ref name="1983/84"></ref> The competition draw paired Porto with the holders Aberdeen, managed by Alex Ferguson. Taking a 1–0 lead to Pittodrie, Porto resisted to the attacking pressure of their opponents. In the 76th minute, Vermelhinho scored the