Buses carrying Santos and Corinthians players were pelted with stones and aluminium cans as Brazilian football was tarnished by fresh waves of violence during the weekend.
The incident occurred as the teams arrived for Sunday's Campeonato Brasileiro match at the Pacaembu stadium, which ended in a 1-1 draw, reported Xinhua.
It came a day after Brazil's Superior Sports Justice Tribunal called for a national debate to curb increasing violence among fans.
According to the tribunal, more than 30 cases involving supporters from Brazil's top four divisions have been heard this year.
In the latest penalty handed out last week, Sao Paulo were stripped of their remaining four home matches of the season for wild brawls involving notorious organised supporter groups.
Four fans of Serie B club America were shot by their Ceara counterparts near Natal city Saturday.
The episodes have cast doubt over Brazil's ability to ensure the safety of crowds during next year's FIFA World Cup.
According to Superior Sports Justice Tribunal President Flavio Zveiter, harsher laws were needed to deter offenders, most of whom escape conviction.
"As long as criminals are allowed to enter stadiums they are going to fight," Zveiter said.
