Flamengo lost 2-1 to Sao Paulo on Thursday but still clinched the Brazilian league title on the final day after challengers Internacional could only draw 0-0 at home to Corinthians.
The result means Flamengo topped the table with 71 points, one more than Inter, and take their second consecutive Serie A title.
Flamengo would have guaranteed their eighth league triumph with a win but looked nervous throughout and in the end they needed their rivals to slip up.
With Inter and Corinthians still playing deep into stoppage time the Flamengo players gathered around a cellular phone on the turf at the Morumbi stadium to monitor the final seconds.
When the whistle went, they erupted with joy.
“It was a real struggle,” Flamengo midfielder Diego said of the game.
“This team really deserves it for all we did. The title speaks of our character, we are winners. It’s so difficult to win back-to-back titles and so now we are going to celebrate.”
Flamengo lost talismanic coach Jorge Jesus before the season started as he returned to Benfica and their early league form was so poor they sat bottom of the table after three matches.
They fired his replacement Domenec Torrent in November and replaced him with Rogerio Ceni.
While Ceni stabilised the team they were given a helping hand by Sao Paulo, who led the table by seven points at one stage but won only two of their last 11 matches.
Flamengo’s win was a personal triumph for Ceni, who won his first major title as manager in the Morumbi stadium, where he was idolised as a player with Sao Paulo.
“It wasn’t the way we wanted,” said the former goalkeeper.
The match itself burst into life seconds before halftime when Sao Paulo's Luciano scored from a free kick to take his season's tally to 18, joint best in the league this season.
Bruno Henrique equalised for Flamengo six minutes into the second period before Pablo restored Sao Paulo’s lead eight minutes later.
In other results, Vasco da Gama beat Goias 3-2 but both sides were relegated to Serie B, along with Coritiba and Botafogo.
(Reporting by Andrew Downie in London; Editing by Peter Rutherford)
