'Big Phil' lost his cool during the post-match media conference, broadcast on Brazilian television, when he was asked why he had fielded midfielder Jorge Valdivia.
The Chile international has been plagued with muscular problems recently and was substituted after only 18 minutes of the game.
"No, no, no, no," said Scolari, grimacing and shaking his head when reporters suggested he had made the wrong decision.
"You lot really are a pain," he said, screwing up his face. "He played for 18 minutes, that's good for me."
"Go you and interview the doctor," added Scolari, his eyes rolling menacingly. "You lot are just clowning around and you're one of the biggest clowns," he said, gesturing towards one television reporter.
Scolari, once a fiery figure who frequently clashed with referees and opponents, mellowed during his stints as Portugal coach and subsequently with English Premier League side Chelsea.
However, the pressures of coaching in Brazil appear to have brought back his more volatile side.
Scolari was also angry after his team were awarded a penalty, only for the referee to change his mind after speaking to his assistant.
"We were told the referee or linesmen received information by radio from somebody outside the four lines (pitch)," he said.
"We will look into it to find out if it was radio or television or where it might have come from.
"This isn't the first time Palmeiras have been awarded a penalty which we didn't get to take."
The teams were meeting in a quarter-final, first leg tie in the Copa Sudamericana, the region's equivalent of the Europa League.
