Australia will play off for seventh at the Rio Olympics after Argentina staged a memorable comeback to win after the siren.
Argentina were behind 21-5 at halftime but kept Australia scoreless in the second half, and scored a try with time up to secure a famous 26-21 win.
Argentina will now face New Zealand for fifth at 7am AEST while Australia take on France at 6.30am AEST.
Australia were off to the perfect start, taking the kickoff and moving easily downfield for a try to Tom Cusack after a nice inside ball from James Stannard.
Cusack was in for a double shortly after with some strong breakdown work from Jesse Parahi forcing the penalty.
The former Wests Tiger then taking the quick tap to offload for Cusack to go under the posts and make it 14-nil after three minutes.
Argentina worked their way into the game shortly after, rolling through the phases only to be denied by a brilliant intercept from John Porch.
Australia then went to counter and were denied with the tryline begging and Argentina reduced to six men after Juan Imhoff slowed the breakdown illegally.
It didn’t take Australia long to make the most of their one man advantage, Con Foley taking the quick tap to take the score to 21-0.
A desperate last ditch tackle from Pat McCutcheon denied a certain try for Argentina as they broke down the wing.
Gaston Revol eventually getting Argentina on the scoresheet, darting through to score on the blindside after a five metre scrum.
Argentina had the better of possession in the second half but ill discipline from both sides slowed the game down.
Australia couldn’t stop Revol from getting a double with four minutes left to play, as the halfback split through Australia’s splintered defence to bring the margin back to eight points.
Mathias Moroni reduced the gap to two after a terrific break from Franco Sabato who offloaded for Moroni to go under the sticks.
With time up, Argentina continued to press as Australia’s scramble defence was put to the test.
It couldn’t hold forever and Moroni eventually forced his way over for a double to secure a memorable comeback.
New Zealand beat France 24-19 to progress through to the fifth place playoff earlier in the day.
Fiji will take on Great Britain for the Gold medal at 8am AEST.
Australia 21 (Tries: Cusack 2, Foley Cons: Stannard 3)
Argentina 26 (Tries: Revol 2, Moroni 2 Cons: Revol 3)