Fla Flu (a truncation of Flamengo Fluminense) is an association football match between cross-town rivals Flamengo and Fluminense. Matches take place in the 78,000-seat Maracan Stadium, located near downtown Rio de Janeiro, in the city's Maracan district.

Flamengo's fiercest and longest-standing rivalries are with the other "Big Four" of Rio de Janeiro: Fluminense, Botafogo and Vasco da Gama. Their Main Rivlary and one of the greatest in Brazilian Football is with Vasco da Gama with which they share the " Clssico Dos Milhes " The Derby of Millions.