Second-placed Flamengo remain the only unbeaten team in the championship and eased to a 2-0 victory over Gremio on Saturday with an inspired Ronaldinho scoring one of the goals in his first ever match against the club where he started his career.
Avai, in 18th place and previously without a home win in Florianopolis, appeared an ideal opponent for Corinthians to recover from their first defeat last weekend and the visitors went ahead through striker Emerson after half an hour.
However, within 14 minutes of the restart, Avai had turned the match around with strikes from forwards William and Rafael Coelho, whose second goal eight minutes from time secured the win despite Jorge Henrique pulling one back in added time.
"We must put our heads in the right place, show maturity. This is a difficult championship. We must see where we went wrong, regroup and get our focus back," said Emerson, who won the title with Fluminense last year and Flamengo in 2009.
Flamengo, who in midweek beat South American champions Santos 5-4 in a spectacular match thanks to a Ronaldinho hat-trick, had the former Barcelona ace in fine form again at home to Gremio.
Ronaldinho, the championship's top scorer with nine goals, laid on the opener for midfielder Thiago Neves at Rio's Olympic stadium in the first half and sealed the win in the second after goalkeeper Victor tried to dribble past him and lost the ball.
Santos lost again in another thriller when they went down 3-2 to Atletico Paranaense at a soggy Curitiba in southern Brazil on Sunday.
Diminutive midfielder Marcinho headed the home side's winner in added-time after Santos recovered from a 2-0 deficit.
