Brazilian champions Fluminense squandered a 2-1 lead and lost 3-2 to Botafogo while Ronaldinho scored his first goal for Flamengo in other matches in Brazil's state championships.
Corinthians' victory in the Sao Paulo derby came after three days of violent protests following Wednesday's upset by Colombia's Deportes Tolima in the preliminary round of South America's elite club competition.
Teenager William Morais was killed in the early hours of Sunday trying to resist a mugger in the city of Belo Horizonte where he was on loan to America-MG.
Right back Alessandro scored the goal that may begin to heal Corinthians' wounds seven minutes from the end of the Paulista state championship match.
Goalkeeper Julio Sergio kept the result safe with some brilliant saves including a remarkable last-minute stop at point blank range from Kleber.
"Because of what we were going through and the importance of a victory, this was without doubt the best match of my career," the 26-year-old keeper told reporters.
"It's still not a happy time but this is a new start for Corinthians."
Palmeiras, trained by former Brazil and Portugal coach Luiz Felipe Scolari, were the better team but were foiled time and again by Julio Sergio's inspired goalkeeping.
Corinthians were without rested former Brazil players Ronaldo, the team's captain, and Roberto Carlos whom fans hold mainly responsible for the Libertadores Cup debacle.
RONALDINHO SCORES
In a pulsating Carioca (Rio de Janeiro) championship match, Argentine German Herrera scored the 64th-minute winner for Botafogo after Uruguay striker Sebastian Abreu had missed one penalty then converted another in the space of four minutes early in the second half.
Fluminense had taken a 2-1 half-time lead with two goals from striker Rafael Moura after midfielder Renato Caja had put Botafogo ahead at the Enganhao stadium in Rio.
The first half ended with both sides down to 10 men after Botafogo's Marcelo Mattos and Fluminense's Colombian midfielder Edwin Valencia were sent off for violent fouls.
In another Carioca championship match, Ronaldinho scored his first goal for Flamengo in his second match since his transfer from AC Milan last month.
Flamengo beat Boavista 3-2 after Ronaldinho had opened the scoring with a penalty in the 24th minute for a foul on striker Deivid.
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