Like many great rivalries, the animosity between Portugal's two biggest cities, and two most successful football clubs, is rooted in the country's political, cultural and sporting history. In the north, there is Porto; a historically working-class, industrial city with a strong independent spirit. In the south, Lisbon; a wealthy, powerful and glamorous capital.
The Porto-Benfica derby embodies this great divide, with a shift in power having intensified the rivalry: As Águias (The Eagles) are historically Portugal's most successful team, while Os Dragões (The Dragons) have been its most dominant force over the last two decades.
The first match between Porto and Benfica was a friendly played on 28 April 1912, with the latter running out 8-2 victors. It would be eight years before Porto secured their maiden success in the fixture, 3-2 in a thrilling contest, and almost another nine before they managed to win again.
Benfica won three Portuguese Liga titles apiece in the 1930s and 1940s, and the Latin Cup in 1950, and with this success, their stock began to soar. It was, however, merely a teaser of what was to come. Spearheaded by the legendary Eusebio, they secured an incredible eight league crowns and two European Cups, courtesy of final victories over Real Madrid and Barcelona, in the 1960s. Benfica continued to prosper domestically in the 1970s and 1980s, but despite reaching three finals, were unable to lift another European trophy.
Porto, after almost two decades without winning the league, claimed successive titles in the late 1970s, and kept their momentum going in the 1980s with another four, plus two Portuguese Cups and one European Cup.
But it was in the 1990s that Os Dragões began to monopolise Portuguese football, winning a record five consecutive league titles. Another five have followed already this decade, along with UEFA Cup and UEFA Champions League crowns.
Facts and figures
In the 240 matches played between the two teams, including friendlies, As Águias have shaded their northern rivals with 94 victories to 91. Both teams have performed much better on home soil: 70 of Porto's triumphs were at Estadio do Dragao, while 72 of Benfica's transpired at the Estadio da Luz.
Benfica remain Portugal's most successful side overall, with 31 league golds, while Porto are their closest challengers on 23. The sides have won Europe's top club prize twice apiece.
The Lisbon giants have over 160,000 registered paying members, and 14 million worldwide. Moreover, they earned a Guinness World Record in 2006 for being the sport's best-supported club. Ironically, Benfica also enjoy a bigger fan-base in the north than Porto.
Some fans feel the rivalry was personified by former players, Joao Pinto (Benfica) and Paulinho Santos (Porto). Despite being international team-mates, they openly declared an intense dislike for one another. Their feud lasted years and derbies would occasionally result in the pair being sent off for brawling.
The intensity of the fixture, however, preceded and superseded the pair's involvement, and the rivalry was recently aggravated by Cristian Rodriguez's move north from the Estadio da Luz. In fact, the Uruguayan became the third Benfica player in recent history to have switched allegiances to Porto.
Both Benfica and Porto have written magnificent chapters in Portuguese football. And having won 23 of the last possible 26 league titles between them, their great rivalry shows no sign of relaxing.