كتب : Hatem Maher
Brazil needed a last-gasp penalty from Kaka to snatch a 4-3 victory over Egypt in Monday's Confederations Cup encounter.
It was the first time in 57 matches that Brazil concede three goals in one match.
Dunga's side next face the US, who failed to defend a one-goal lead to lose 3-1 to Italy in their tournament's opener.
After seeing Egypt match Brazil for most of their clash, Donovan sees no reason why the US can't cause an upset in Thursday's tie.
"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 told FIFA.com.
"We hung with Italy and gave them a hard game, made things very complicated for them for a large part of our first game.
"I don't see any reason why we can't do exactly that against the Brazilians too."
The US had Ricardo Clark dismissed against Italy but still managed to take the lead through a Donovan penalty.
However, their numerical disadvantage couldn't help them keep their slender advantage as Italy roared back in the second half to emerge winners.
"We will have an even better chance if we can keep 11 men on the field," Donovan added.