The youngster opened the scoring to put the dominant Samba boys ahead in the first half, setting the home side on the path to victory against its continental rivals.
After a 0-0 deadlock in the first leg in Argentina two weeks ago, the 19-year-old Lucas opened the scoring in the second-half with a 50 yard run and finish on the counter, before Neymar sealed the victory with a close-range finish which bobbled over the line thanks to an Argentine deflection.
Spurred on by a fanatical home crowd in Belem, which exploded with shrill screams every time Neymar in particular received the ball, Brazil dominated proceedings throughout the first 45 minutes. The Argentines looked solid at the back, but were pinned in their own half by the incursions of the Selecao wide men and offered little attacking threat.
Teenage starlet Lucas was in electric form in the first 45 minutes, and tortured the Argentine defence with his running from deep. In the opening stages he stormed forward before firing just wide, and even a bloody nose following a forearm in the face from Emiliano Papa did not slow him down.
Alejandro Sabella's team attacked with a little more purpose after half-time, and Augusto Fernandez came close to giving the visitors a surprise lead. The Velez man smashed the ball to force a save from Jefferson, but seconds later it would be Brazil in the ascendancy.
The Argentines were caught hopelessly out of place following a corner, and Lucas was released on a blistering counter-attack. The youngster easily outstripped the chasing Desabato and Papa and slotted with assurance past Orion to score the first goal of the two-game series.
The strike lifted the Canarinha, and the creative trio of Neymar, Ronaldinho and Lucas streamed forward at will as they finally appeared to be enjoying the friendly clash. Only some determined last-ditch defending prevented the Argentines slipping further behind as the pressure built, although this came at the expense of any real offensive capability.
The visitors still came forward in sporadic bursts, one of the best chances occurring when substitute Mario Bolatti forced a simple save with a weak header. Brazil, though, looked supremely comfortable, and sealed victory with 15 minutes left when Neymar bundled in from close-range to polish off a fluid passing move - much more fluid in fact than the dancing which followed the goal.
The win hands Mano Menezes' side victory in the first-ever Superclasico de las Americas series, and is more than welcome for a coach who had seen the pressure build after the Copa America.