S.L. Benfica 2015, Benfica reported to have 246,401 members; however, after a scheduled renumbering by the club in August 2015, the number decreased to 156,916. In April 2017, Benfica reported they had a total of 184,264 members by 31 December 2016. Benfica has rivalries with Sporting CP and FC Porto, with whom it forms the "Big Three": Portugal's most decorated clubs. None of them have been relegated from the Portuguese league since its establishment in 1934. As Lisbon-based clubs, Benfica and Sporting have shared a rivalry for over a century; it all started in 1907 when eight prominent Benfica players defected to
1980–81 S.L. Benfica season in a row, including a home win against Porto on 14 March in the Clássico, which gave them a four-point lead with seven matches to go. At the same time, in the Cup Winners' Cup, Benfica beat Fortuna Düsseldorf at home, after a 2–2 away draw, qualifying for the semi-final. March closed with another draw, now with Académico de Viseu, removing a point from their lead over Porto. On 8 April, Benfica met Carl Zeiss Jena for the first leg of the semi-finals, losing 2–0. Four days later, they drew with Vitória de Guimarães, and saw his lead drop to