Flamengo said Thursday it retired the No. 12 jersey, symbolizing the importance of the team's so-called 12th man.
"The jersey belongs to the 'athlete' that honored the red and black colors (of Flamengo) the most," team adviser Reginaldo Beltrato said in a letter that prompted the decision. "This 'player' never missed a single match and helped the team to victory in the most difficult situations."
Flamengo has the largest fan base in Brazil, with about 33 million supporters in the nation of about 180 million people.
Flamengo is Brazil's most successful club, with five Brazilian league titles, but most of its glories date back to the 1980s, when all-star playmaker Zico was still in action. The club has struggled in recent years, winning only a few Rio de Janeiro state championships and a single Brazilian Cup title.
It has failed to contend in the Brazilian league and barely avoided relegation on several occasions. The last time it was a contender was in 1997, when it finished fifth.
Flamengo fans helped pack Maracana last Sunday in a 2-0 loss to rival Fluminense. The more than 60,000 fans at the stadium marked the biggest crowd of the season in this year's Brazilian league.
Flamengo is currently 13th in the 20-team standings with 40 points from 29 matches. Its next match is Saturday at Parana.