Defender Maicon dropped from Brazil squad
The Roma full-back was axed from the national setup on Sunday, with technical director Gilmar Rinaldi refusing to expand on the reasons for his departure.
Maicon played the full 90 minutes in Friday's 1-0 win over Colombia in what was new coach Dunga's first match in charge since being re-appointed to lead the Selecao.
The 33-year-old Maicon had been widely considered to be a key part of Dunga's plans, as he seeks to restore Brazil's pride and standing within the international game following their humiliating 7-1 World Cup semi-final exit at the hands of eventual winners Germany.
Maicon has won more than 70 caps for his country, having made his debut back in 2003 against Mexico.
However, his international future is now shrouded in uncertainty after Rinaldi confirmed that he had been released from the squad.
"I thank him for coming to the Selecao, but today he was disconnected from the delegation," Rinaldi was quoted as saying by the Brazilian media.
"We thank him for his services... it was an internal problem, I will not answer questions about it and would like to kindly ask that you do not ask the players."
A statement on the Brazilian Football Confederation's website confirmed that Monaco defender Fabinho has been called up to replace Maicon for the clash with Ecuador at the MetLife Stadium in New Jersey on Tuesday.
The news leaves Dunga with a defensive headache for the meeting with Sixto Vizuete's side, with David Luiz having been ruled out earlier on Sunday after suffering a knee injury.