Firmino was substituted after landing awkwardly in Liverpool's 3-2 League Cup penalty shootout win over fourth-tier Carlisle United at Anfield on Wednesday.
"Ricardo Oliveira, the top goalscorer in the Brazilian league with 17 goals, was called up by Brazil coach Dunga," the CBF said in a statement.
"The Santos striker will take the place of Liverpool striker Firmino, who was released because of injury."
Brazil, who have never failed to qualify for the World Cup finals, face Chile in Santiago on Oct. 8 and then return home to play Venezuela five days later.
Oliveira has six caps and last played for Brazil in 2006.
(Writing by Andrew Downie; Editing by Ken Ferris)
