Flamengo's fiercest and longest-standing rivalries are with the other "Big Four" of Rio de Janeiro: Fluminense, Botafogo and Vasco da Gama; as well as interstate rivalries with Atletico MG and Palmeiras.

The Clssico dos Milhes (English: Derby of Millions) is the name given to Flamengo and Vasco da Gama association football derby, both teams from the city of Rio de Janeiro, Brazil. Considered as one of the most fiercely contested derbies in Brazilian football, both in historic rivalry and in popularity.