Cristovao Borges' Fluminense eased to a 3-0 victory over newly promoted Figueirense on Saturday, while Sao Paulo accounted for Botafogo by the same scoreline on Sunday.
Fluminense finished a disappointing 15th last season, just two points above the relegation zone but the Rio-based outfit got their season off to the perfect start at the Estadio Jornalista Mario Filho.
Star man Rafael Sobis got Fluminense on their way with a 31st-minute opener before Fred doubled the home team's advantage courtesy of a penalty on the stroke of half-time.
The game was put to bed on the hour-mark when Fonseca Nirley put the ball into his own net.
Fluminense have now kept back-to-back clean sheets in all competitions, scoring eight goals in the process.
Meanwhile, Sao Paulo easily disposed of Botafogo, who seem set to struggle without Clarence Seedorf and Rafael Marques.
It took Sao Paulo just 13 minutes to register their first goal, former Botafogo player Antonio Carlos doing just enough to get the ball over the line in his national league debut for Muricy Ramalho's men.
It was looking all too easy for the hosts as they doubled their lead through Douglas, who was played in by Alexandre Pato on 22 minutes.
The visitors were guilty of committing too many men forward and Sao Paulo were able to find the gaps, Ganso squaring to Brazil international Luis Fabiano for an easy third.
Meanwhile, defending champions Cruzeiro left it late to beat Bahia on Sunday.
Nilton had given Cruzeiro a 63rd-minute lead before Taslica restored parity from the penalty spot with 10 minutes remaining.
However, the visiting side left the Itaipava Arena Fonte Nova with maximum points thanks to Marcelo Moreno's 90th-minute winner.
Palmeiras were also triumphant in round one, with Leandro and Alan Kardec scoring in the final seven minutes to prevail 2-1 at Criciuma.
Elsewhere over the weekend, Internacional recorded a narrow 1-0 win at home to Vitoria and Atletico PR edged Gremio 1-0.
Gabriel scored 10 minutes from time as Santos earned a 1-1 draw against Sport Recife.
Atletico Mineiro and Corinthians could not be separated, playing out a scoreless draw at the Estadio Municipal Joao Havelange.
Flamengo drew 0-0 with Goias, while the score was the same between Chapecoense and Coritiba.
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