The Paris Saint-Germain defender suffered cartilage damage to his left knee during Friday's 1-0 victory over Colombia in Miami and will miss Tuesday's meeting with Sixto Vizuete's side.
A statement on the Brazilian Football Confederation's (CAF) website on Sunday confirmed: "David Luiz suffered an injury to the cartilage of the patella in his left knee during the game against Colombia, and is unable to play on Tuesday [against] Ecuador.
"The player did tests, under the assistance of the Brazilian team, who observed the clinical diagnosis made by the medical doctor."
The news comes as a blow to new coach Dunga, who has returned to lead the Selecao following their humiliating 7-1 semi-final exit from the World Cup at the hands of eventual winners Germany.
Dunga is already without Luiz's centre-back partner and club colleague Thiago Silva, who suffered a hamstring problem in pre-season.
Neymar has replaced Silva as captain of the national team since the World Cup and will again lead the side in midweek, with his goal having proved decisive against Colombia.
