The rivalry comes about as Lisbon and Porto are the two largest cities in Portugal, and the two clubs are two of the wealthiest, most successful and influential football teams in Portugal. The animosity between these two sides also extends from the country's political, cultural and sporting history.
The first match between the Águias and the Dragões was an exhibition game that was played on the 28 April 1912, where Benfica defeated Porto 8–2. Eight years later, Porto would win their first Clássico, after beating their rivals Benfica 3–2. Porto would have to wait another nine years to accumulate their second victory over Benfica. Prior to the establishment of the Primeira Liga in 1934, both Benfica and Porto were competing within their football league district. Both sides were also competing in the Campeonato de Portugal which later became in 1938 the Taça de Portugal.
Up until 1934, Benfica would win the Campeonato de Lisboa nine times as well as triumphing in the Taça de Honra de Lisboa twice, whilst Porto would win the Campeonato do Porto nineteen times as well as claiming the Taça de Honra do Porto twice. Benfica would meet Porto for the very first time in an official match in the domestic cup competition which during the early periods of Portuguese football was the Campeonato de Portugal. Benfica defeated Porto in the final of the 1931 Campeonato de Portugal, 3–0 at the Campo do Arnado in Coimbra. Two from Vítor Silva and one from Augusto Dinis sealed the win to claim Benfica's second Campeonato de Portugal.
The inception of the Primeira Liga, saw Porto win the very first edition of the competition. Both sides met for the very first time in the competition on the 3 February 1935, where Porto triumphed over their rivals 2–1. Benfica would win the return tie 3–0. Despite Benfica's win, the Águias would finish third in the league, three points behind Porto. The next five seasons would see Benfica win three and Porto win two league titles. When the 1940s arrived, both sides would take a back seat to Sporting CP, who would win five league titles in a decade.
The late 1950s and 1960s saw Benfica dominate not just Portuguese football but also European football. The arrival of Eusébio saw Benfica secure eight league titles in the space of ten years. Benfica's league titles were joined by two consecutive European Cups which were won in 1961, 3–2 against Barcelona, and in 1962, 5–3 against Real Madrid. The 70s saw the continuation of Benfica's dominance up until the 1977–78 season, where Porto secured the league title for the first time in nineteen years. The 80s and early 90s saw both Benfica and Porto battle for the league title. Porto's resurgence and the introduction of Pinto da Costa as chairman saw Porto reach new heights, winning the European Cup for the first time after beating Bayern Munich, 2–1 in the 1987 European Cup Final. Three years later Benfica reached their eighth European final, the 1990 European Cup Final, where they lost to Milan 1–0.