Sao Paulo rode a wave of enthusiasm from a record crowd at the at the Morumbi stadium where new signing Paulo Henrique Ganso was unveiled on Sunday before a 1-0 victory over Cruzeiro.
Striker Osvaldo's winner in front of the season's record crowd of 40,457 kept Sao Paulo firmly in fifth place with 42 points from 26 matches, 14 points behind leaders Fluminense and in touch of the top four who will qualify for next season's Libertadores Cup, South America's continental championship.
Fluminense, who beat Nautico 2-1 on Saturday, benefited from the 0-0 draw between their closest rivals Atletico Mineiro and Gremio. The tie left 'Flu' four points in front of Mineiro, who have a game in hand, and seven ahead of Gremio.
Sao Paulo announced on Friday they had signed 22-year-old Ganso from big rivals Santos for a reported $12 million and officially presented the gifted Brazil playmaker before kick-off.
Ganso helped Santos win the Libertadores Cup last year but there is no fixed date for the injury-prone midfielder's debut since he arrived at Sao Paulo with a left thigh problem.
The crowd beat the season's previous best in the first division of 38,862 at the Flamengo-Fluminense derby in Rio.
The average crowd in the first division, however, is around 12,000 since the main stadiums are closed and undergoing work for the 2014 World Cup finals.
At the bottom end of the standings, Palmeiras marked Gilson Kleina's debut as Luiz Felipe Scolari's replacement as coach with a 3-1 win over Figueirense on Saturday.
Palmeiras' sixth win in 26 matches lifted the team into 18th place and within five points of Coritiba, the lowest placed team outside the relegation zone.
Flamengo ended a run of seven matches without a win by beating bottom side Atletico Goianiense 2-1 and are now 14th.
Dutch former AC Milan and Real Madrid midfielder Clarence Seedorf had another fine game in his first season in Brazil scoring both goals for sixth-placed Botafogo in their 2-2 draw with South American champions Corinthians.comments