Brazil's first mission is to register a win that will guarantee them a spot in the competition's semi-final, after they beat Egypt 4-3 in their first game.
The second task is trying to produce a performance that can change the shaky face the Selecao showed against Egypt on Monday.
Kaka and co. needed a last gasp penalty-kick to beat the Pharaohs in a highly entertaining clash where Egypt dominated most of the play.
Despite saying that his team were affected by the long journey to South Africa in their first game, Dunga understands that the second clash won't be easier than the Egypt win.
"USA are a team set up very well, very obedient tactically," Dunga said.
"They have proved an adversary very tough to Brazil and to all of its opponents recently. It usually doesn't allow three goals like it did against Italy."
Similar to Egypt against Brazil, the Americans produced a courageous and respectful display in the 3-1 loss to Italy in heir first match.
Striker Landon Donovan takes heart from his country's showing against the world champions, adding that they can go even further against Brazil.
"We hung with Italy and gave them a hard game, made things very complicated for them for a large part of our first game," the former Bayern Munich man said.
"I don't see any reason why we can't do exactly that against the Brazilians too.
"We had the opportunity to see some of their (Brazil's) game against Egypt and I have to be honest, it looks like they're human after all," he added.