Palmeiras coach Luiz Felipe Scolari, whose side beat Atletico Paranaense 2-0 on Saturday to end a run of six matches without victory, could be suspended for up to six games after being escorted off for excessive criticism of the referee.
Fluminense took advantage of Inter's decision to field only two first-choice players, goalkeeper Renan and midfielder Tinga, ahead of Wednesday's second leg of the Libertadores Cup final at home to Guadalajara of Mexico.
Right-back Mariano's left-footed shot in the 20th minute was deflected past Renan and three minutes later Conca's near-post corner was headed home by striker Washington for the second.
Before kick-off, Flu's newly-signed midfielder Deco was greeted with rapturous applause by a crowd of nearly 60,000 at the Maracana.
The former Porto, Barcelona and Chelsea player will make his debut next weekend's in the derby with Vasco da Gama at Rio's giant stadium.
"This is all fantastic. I've never experienced anything like it before and I hope to repay this affection with titles," the 32-year-old, back in the country of his birth after 13 years in Europe, told reporters.
The demonstrative Scolari, who was Deco's coach with Portugal and Chelsea, has found it hard to contain his his feelings due to his team's lowly position and the fear of relegation.
