Doriva was sacked as manager of bottom club Atletico-GO, while Alexandre Gallo was ousted at Vitoria, who are one place above them.
Roger was replaced as manager of Atletico Mineiro on Thursday and Pachequinho was sacked by Coritiba the day before.
In all, half the top division's 20 clubs have changed their coaches at least once since the season started on May 13, and three clubs have changed coaches twice.
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Last season, 32 coaches were fired over the course of the 38-game season.
Corinthians top the current league table after 15 matches, with a six-point lead over second-placed Gremio.
(Reporting by Andrew Downie; editing by John Stonestreet)
