Corinthians surprised compatriots Santos as they claimed a 1-0 away win in the first leg of their Copa Libertadores semi-final.
Emerson Sheik netted the only goal of the game, helping the Brazilian league winners take a slender advantage over the defending Libertadores champions.
Tite's Corinthians, who have made a disappointing start to their domestic campaign, will have a great chance to seal a place in the final in the second leg to be played in Sao Paulo next Wednesday.
They will have to do it without Emerson, though, as he was sent off late on.
Corinthians played as if they were the home team at the Estadio Vila Belmiro, as they managed nullify the threat from Santos star Neymar almost completely.
It was Santos though who had the first chance in the seventh minute, when Elano fired a free-kick straight into the hands of keeper Cassio.
Corinthians opened the scoring in the 28th minute. Alex passed the ball to Paulinho, who sent the ball to Emerson and the attacker controlled the ball before driving it into the top left corner.
Corinthians controlled the game from there, even after Emerson was sent off in the 76th minute for a tough challenge on Neymar, an incident which sparked a melee among players from both sides.
The drama was still not over as, six minutes later, the lights went out and the match was stopped for almost 20 minutes.
Santos could do nothing to alter the scoreline when play eventually resumed.
Corinthians will make it into the final with a draw next week to face either six-time Libertadores champions Boca Juniors or Universidad de Chile.
Corinthians midfielder Paulinho told O Globo TV: "It was not easy at all. This is what Corinthians are like. We won but we suffered a lot.''
Defender Fabio Santos added: "We have to respect Santos. They are the reigning Libertadores champions and we just earned a good victory. There are 90 minutes left.''
Paulo-Henrique Ganso, who returned to Santos line-up 18 days after he underwent an arthroscopic surgery on his knee, said: "We played well in defence but we lacked cutting edge.''
He added that the loss of Emerson for the second leg could be crucial, saying: "Corinthians lost one of their best players and we have what it takes to get past them. We have to work hard.''