The Santos attacker helped the Selecao to victory with his goal well into stoppage time after previously providing the assist for the equaliser
Juan Manuel Martinez opened the scoring for the away side midway through the first half, but Paulinho restored parity shortly after. Neymar then decided the game well into stoppage time as he slotted home a penalty.
The hosts started the match the better side of the two, yet it were the Argentines who broke the deadlock after 20 minutes of play. A good team move eventually saw Martinez in a dangerous position and the forward beat Jefferson with a good volley.
Brazil responded in kind; Paulinho netted the equaliser six minutes later. The Argentina defence allowed the Corinthians midfielder too much space after a Neymar free kick, and he headed home from close range to make it 1-1.
The home side dominated play in the remainder of the game, but the fans had to wait until the dying minutes of the game for Brazil's second goal.
Leandro Desabato handled the ball inside his own area, leaving the referee no other choice but to award a spot kick. Neymar stepped up to take it and made no mistake from 12 yards.
The second leg will be on October 3 at the Bicentenario stadium in Resistencia City.