Leaders Palmeiras lost 3-2 away to Vitoria while Inter squandered the chance to take over at the top when they went down by the same score at home against mid-table Cruzeiro.
Sao Paulo, who beat Avai 2-0 at home on Saturday with two second-half goals by striker Dagoberto, have 43 points from 24 matches, one point less than Palmeiras and behind Inter on goal difference.
Cruzeiro, who are 13th in the table, were inspired by Gilberto, who scored twice and started the move for their third goal.
The 33-year-old equalised with a 37th-minute penalty after Alecsandro had put Inter ahead, also with a penalty.
Gilberto then put Cruzeiro ahead nine minutes into the second half when he headed home a cross from the right.
Inter levelled with a free kick by substitute Andrezinho with 16 minutes to go before Thiago Ribeiro hit Cruzeiro's winner a minute later following a rebound off keeper Lauro.
"We know this 13th place doesn't reflect the quality of the Cruzeiro team and we're going to chase the top four (Libertadores Cup qualifying places), that's our objective," Gilberto told reporters. "The title is harder but we can get back into the Libertadores next year."
FREAK GOAL
Palmeiras fell behind after 20 minutes to a freak goal by midfielder Uelliton when the ball hit his head and went in from a poor clearance by goalkeeper Marcos.
The league leaders equalised before halftime through substitute Robert but Vitoria reclaimed the lead in the 71st when Beto Berola scored from close in.
Derlei scored Vitoria's third goal five minutes from time from a corner before Robert pulled one back with a header from Paraguayan Jose Ortigoza's cross.
"The championship is very balanced, today we made too many mistakes but we had some luck, at least our nearest rivals also did badly," said coach Muricy Ramalho, who steered Sao Paulo to the last three national titles.
Recalled Brazil striker Adriano continued his good form with two goals in Flamengo's 3-0 victory over Sport Recife at the Maracana on Saturday.
The former Inter Milan striker, who hit the opener from the edge of the box and added a last-minute header from a corner, is the championship's joint top scorer with 12 goals.
