Chasing what would be a first gold in 10 attempts, Hugh McCutcheon's side were almost faultless in front of a boisterous crowd, sending out the clearest of signals that 2012 could be their year.
Backed by the support of USA Basketball star Kobe Bryant - off-duty this afternoon - they got to grips with Brazil's delicate style before blowing them off the court by way of the brilliance at the net of Destinee Hooker and Foluke Akinradewo.
With Brazil struggling to get to the floor - especially with American's exceptional libero Nicole Davis dealing with all that came her way - they found themselves under increasing pressure and, after falling 12-11 behind, were never ahead again in the first set.
Twice Hooker shut down Jaqueline Carvalho and, with Jordan Larson chiming in with a potent spike, the set was seen out in surprisingly easy fashion.
The second set carried on in a similar vein, with America never behind at any stage, with their dominance so strong that they led by 10 points on two occasions.
It appeared that Brazil were headed for a straight-sets loss at that stage, but they finally clicked into the form that they are renowned for, roaring back to win the third owing to a change of approach.
Rather than looking to tip around USA's dynamic front row they opted to stand toe-to-toe with them, taking them on in the air, with Sheilla Castro plundering 13 points from the spike alone.
But they could not carry that momentum into the fourth set, with 23-point Hooker and the brilliant Larson returning to the form they had displayed in the opening two sets to see the game out.
Elsewhere, China beat Turkey 3-1 and there was also success for Host Nation Great Britain, who went beyond midnight to go the distance against Algeria at Earls Court and were rewarded with a first-ever win in Olympic Games competition.
Republic of Korea, Russia and Italy also came away with the points on an action-packed day.