Portuguesa fire coach after first game of season
Soares was dismissed following Wednesday's 1-0 defeat by Guarani in their opening Paulista (Sao Paulo state) championship match, the club said on their website.
He took over in August and was in charge for a total of 17 games. Last season Portuguesa were relegated to the second division of the Brazilian championship.
Mario Sergio's previous job was a nine-match stint with Figueirense last year. He quit with four matches of the campaign left and the team were eventually relegated.
The Paulista is one of a plethora of regional tournaments which serve as a warm-up to the Brazilian championship.
Brazilian football has one of the highest turnovers of coaches. The 2008 season produced 35 coaching changes among the 20 first division clubs.