Abel Braga's Internacional came from behind to beat Atletico PR 2-1 at the Estadio Jose Pinheiro Borba on Saturday.
Internacional had trailed with 38 minutes remaining but Andres D'Alessandro and Alan Patrick scored in the space of 13 minutes to send the club clear at the summit.
The three-time champions sit ahead of Fluminense, who returned to winning ways with a 2-0 victory over strugglers Flamengo to occupy second spot.
After a goalless opening 45 minutes, Atletico PR broke the deadlock seven minutes into the second half, albeit with some help from Internacional.
An attempted interception from an Internacional defender fell to the feet of Marcos Guilherme, who made no mistake from close range.
Internacional quickly responded, however, with former Argentina international D'Alessandro carefully side-footing his shot from outside the area just two minutes later.
The home side completed their comeback in the 67th minute after Patrick, on loan from Ukrainian giants Shakhtar Donetsk, unleashed a powerful long-range shot past Atletico PR goalkeeper Weverton.
Internacional's win moved them clear of Corinthians, Cruzeiro and Goias, who all slipped up over the weekend.
Corinthians, unbeaten thus far, remain third in the standings after drawing 1-1 at Sao Paulo, who were held to their third consecutive stalemate.
Defending champions and fifth-placed Cruzeiro lost 2-1 as Atletico Mineiro claimed their first win of the season against a team that finished with nine men.
As for eighth-placed Goias, they were beaten 2-0 by Palmeiras.
In other results over the weekend, Daniel netted a hat-trick as Botafogo routed Criciuma 6-0.
The 20-year-old Brazilian midfielder scored three goals in the space of 18 minutes in the second half to inspire the home team.
Emerson Sheik bagged a brace, while substitute Wallyson scored late on.
Bahia climbed up to fourth in the standings after playing out a 1-1 draw at home to Vitoria.
Unbeaten Santos downed Figueirense 2-0 in a match that saw both teams reduced to 10 men in the second half.
Elsewhere, Hernan Barcos scored twice as Gremio defeated lowly Chapecoense 2-1, while Rithiely struck late to help Sport Recife to a 1-0 win against Coritiba.
