League leaders Cruzeiro were held to a 3-3 draw, despite a first-half brace from Julio Baptista, after 18-year-old substitute Kenedy equalised for Fluminense with two minutes remaining in Rio de Janeiro on Sunday.
Cruzeiro - 11 games unbeaten in a span stretching back to May 28 - remain top of the table with 43 points from 19 matches.
With the competition's leading goalscorer Ricardo Goulart and midfielder Everton Ribeiro away on international duty with Brazil in the United States, former Real Madrid and Arsenal forward Baptista was promoted to Marcelo Oliveira's starting XI.
Cruzeiro's lead lasted three minutes as hosts Fluminense hit back courtesy of Wagner's header on the goal line.
Fluminense were ahead six minutes later after an unmarked Dario Conca drove into the penalty box and found Cicero, who guided the ball through Fabio's fingers.
Cruzeiro's Bolivian star Marcelo Moreno scored in his sixth consecutive game - making it eight goals in the process - after volleying the ball past Fluminense goalkeeper Klever in the 58th minute.
But Fluminense salvaged a point two minutes from time thanks to Kenedy's curled effort from the edge of the box.
A seventh-minute own goal from Rithiely and Alexandre Pato's 26th-minute strike saw Sao Paulo make it seven league games without defeat.
Internacional cruised to the half-time break with a 2-0 lead thanks to Andres D'Alessandro's 18th-minute penalty and Paulao's thunderous effort from inside the penalty arc after 35 minutes.
Gremio were banned from this year's competition after their fans' racial slurs against Santos.
But Luan's 90th-minute goal gave Luiz Felipe Scolari's men victory, while Flamengo lost for the first time in five league matches.
