Striker Wellington Paulista headed in from a pass by Argentine playmaker Walter Montillo in the first half as Cruzeiro defeated Fluminense 1-0 to claim the Brazilian league lead on Sunday.
Cruzeiro now has a two-point lead over Fluminense and a five-point advantage over Corinthians, which lost 4-3 to lowly Atletico Goianiense at home to extend its winless streak to five matches. Corinthians coach Adilson Batista quit after the loss.
In the much-anticipated matchup between the top two teams in the standings, Cruzeiro edged Fluminense to take the lead for the first time with nine rounds to go.
"I'm happily surprised with how things are going for me and for Cruzeiro," said Montillo, who arrived at the club in August.
Cruzeiro, seeking its second national title, has won four of its last six matches.
Fluminense, winless in its last three matches, lost at Uberlandia despite the return of former Chelsea playmaker Deco, who started at midfield alongside Argentina's Dario Conca.
Corinthians, still without unfit striker Ronaldo, jumped ahead of Atletico Goianiense just two minutes into the match at Pacaembu stadium in Sao Paulo, but allowed four unanswered goals and failed to recover to the disappointment of the nearly 30,000 fans.
Corinthians played a man down from the 58th minute after defender Leandro Castan was sent off for elbowing an opponent in a ball dispute at midfield.
Batista announced his decision to leave the team moments after the match ended, telling club directors in the locker room that he was quitting for the good of the club. Batista took over Corinthians in August to replace Mano Menezes, who accepted the Brazil national team job after the World Cup.
Corinthians has a game in hand - against Vasco on Wednesday in Rio de Janeiro.
Defending champion Flamengo, in its second match with former Brazil and Real Madrid coach Vanderlei Luxemburgo, relinquished a two-goal lead to draw Avai 2-2 at Florianopolis. Val Baiano scored both goals for Flamengo, which is only 14th in the standings and remains in danger of relegation.
The six-time champion played with 10 men from the 58th minute after defender Leo Moura was shown a second yellow card for a hard foul.
Also Sunday, Luiz Felipe Scolari's Palmeiras held Joel Santana's Botafogo to a scoreless draw at Engenhao stadium in Rio de Janeiro, extending its unbeaten streak to six matches.
Uruguay striker Sebastian Abreu missed a ninth-minute penalty for Botafogo, which hasn't won in eight rounds.
Botafogo, sixth in the standings, played Sunday's match without several key players, including Argentine striker German Herrera.
Palmeiras' Chilean playmaker Jorge Valdivia, who scored twice in the team's 4-1 win over Avai on Thursday, was substituted in the second half. The four-time national champion remains ninth on the table.
Copa Libertadores champion Internacional beat Atletico Mineiro 1-0 at the Beira-Rio stadium in Porto Alegre, moving to fourth in the standings with 47 points and a game in hand - against Santos.
On Saturday, Santos kept its title hopes alive by beating Atletico Paranaense 2-0, moving to fifth place with 45 points.
Six-time champion Sao Paulo beat last-place Prudente 3-2 with three goals by former AC Milan striker Ricardo Oliveira for its second consecutive win under former Paraguay coach Paulo Cesar Carpegiani. Sao Paulo remains 10th in the standings.
Gremio's four-match winning streak ended with a 3-3 draw with Vasco at Sao Januario stadium in Rio de Janeiro. Striker Jonas scored twice for Gremio, taking his league-leading tally to 19 goals. Jonas has scored 11 goals in the last eight matches, including five in the last two.
