1st phase: 2 groups of 8 teams. Single split round-robin system (see early 1970 tournaments) i.e. teams for one group played first only the other group's teams in a first stage then played in single round-robin with their own group teams in a second stage, thus featuring a full single round-robin with all 16 teams. For each group, champions of each stage qualified and played an extra double play-off. Oddly, if one team happened to win both stages, it would still be obliged to play an extra double play-off (with home and draw advantage) against its own group second-stage runner-up (most oddly, it was not against the remaining overall stage runner-up), instead of directly proceeding to 2nd phase. As it happened, Atlético Mineiro and Sport, while winning both stages, had to play against Flamengo and Bangu, despite Grêmio and Vitória respectively featured better season record. While Sport managed to confirm their advantage, Atlético Mineiro was eliminated, despite an 8-point season record lead over Flamengo.