The Hoffenheim attacking midfielder came off the bench to settle a scrappy friendly on Sunday and showed his quality to round Claudio Bravo and tap home the only goal.
With Firmino not yet guaranteed his place in Dunga's Copa plans, the 23-year-old says he would play anywhere if it meant featuring at the tournament.
"I'm happy. I took my chance. That's what I have to do," he told Globo TV following the 1-0 win in north London.
"Hopefully in these games I've done enough [to go to the Copa America].
"I don't mind where I play - in midfield, up front - but wherever it is I'll give my all."
In the sides' first meeting since the World Cup, Brazil were again given a thorough workout by their Copa America hosts.
Robinho added: "It was a good test, a good victory. Chile are a very strong team - very fast, with good movement.
"But we played a good game. It was great preparation for the Copa America. The World Cup is in the past. We're focused [on the Copa America]."
