Brazilian championship leaders Sao Paulo suffered their second 1-0 defeat in four days on Sunday when they were beaten by relegation-threatened Corinthians.
Defender Betao headed the only goal four minutes from time to give Corinthians their first win in three games under Nelsinho Baptista, their fourth coach of the year.
It was also the first time they had beaten local rivals Sao Paulo since 2003.
The win failed to pull Corinthians out of the relegation zone, leaving them 17th in the 20-team table with 37 points from 30 games. The bottom four go down.
Second-placed Cruzeiro failed to take advantage of Sao Paulo's slip-up when they were held 0-0 by lowly Goias.
Defending champions Sao Paulo, who have 63 points, are still 11 clear of Cruzeiro with eight games to go after their fifth defeat in 30 games.
Third-placed Santos closed the gap on Cruzeiro to one point by beating hapless Botafogo 2-1 on Saturday with an 89th minute goal from Renatinho.
Rodrigo Tabata had put Santos ahead with a 50th minute penalty and Dodo fired the equaliser in the 66th minute.
It was Botafogo's third defeat in eight days under new coach Mario Sergio.
The weekend's results left only five points between Sport Recife in seventh place and Corinthians in 17th.
Atletico Mineiro, under former Brazil coach and goalkeeper Emerson Leao, won for the first time in eight matches, coming from behind to beat Sport Recife 3-1.
Atletico are 16th, ahead of Corinthians on the number of games won.
Fluminense beat Flamengo 2-0 in the "Fla-Flu" derby in Rio de Janeiro after Somalia and Thiago Neves scored at the start of each half.
