Lachlan Wales opened the scoring for the Olyroos in the 14th minute. Francisco Ortega was sent off at the end of the first half, reducing the Albicelestes to ten men. Marco Tilio doubled the lead in the 80th minute as Australia won their first Olympic match since 2004.
Story of the match
Australia signalled their intent early on as Daniel Arzani looked lively down the left early in the match, as he carved out a few openings with his clever movement and Nathaniel Atkinson was dangerous with his bombing attacking runs from right full-back stretching the Argentine defense.
The Olyroos took a shock lead in the 14th minute as Harry Souttar played an inch-perfect free kick from his own half to Joel King on the left flank, who managed to cross the ball first-time through the penalty area.
Mitch Duke was in great position to make contact but he missed the shot before Wales arrived at the back post to sweep the ball into the net.
Argentina had an excellent chance to equalise shortly after as Carlos Valenzuela cut inside and his shot was blocked by captain Thomas Deng. Later on, Fausto Vera tried one from long range that had Australian goalkeeper Tom Glover scrambling, but the shot drifted wide of the post.
The Olyroos nearly doubled their advantage as Riley McGee who executed a bicycle kick in the penalty area but the ball landed in the arms of the Argentina keeper Jeremias Ledesma.
The Albicelestes were nearly level as Ezequiel Barco saw his cross fly over Glover's head and bounce off of the crossbar. The turning point of the match would soon follow.
On the stroke of halftime, having already been booked, referee Srdjan Jovanovic handed Ortega a second yellow card in 30 seconds as Australia was about to take a corner on what looked to innocuous contact with Riley McGree.
After the break, the Olyroos immediately tried to capitalize on their man advantage, with Duke clipping the crossbar with a delightful dink inside of 20 seconds and Arzani having a long-range shot parried away by Ledesma.
McGree had a golden chance to kill off the game as he was put through on goal with Wales in support, but a poor pass meant he had to adjust before his shot forced the Argentine netminder into a wonderful point-blank save.
But Australia did manage to wrap the game up with 10 minutes to play, as substitute Tilio swept home a wonderful strike from outside the area with his second touch, after his first played the ball to Duke for the assist.
There could have even been a third for the green and gold in stoppage time, but Duke poked a shot just wide of the post with a golden opportunity.
Man of the match: Mitchell Duke
One of Australia's three overage players, Duke was superb. His work-rate was first-class, he held the ball up brilliantly and the assist on Tilio's goal was wondrous.