La Albiceleste dominated swathes of the game and jumped ahead early. Fausto Vera's cool finish in the fourth minute put the Amajita in catch-up mode, but South Africa embraced that role in the first half and drew even through Keenan Phillips in the 23rd minute.
Though South Africa were able to exert some control in the first 45 minutes, Argentina took command as the game wore on. Ezequiel Barco's second-half brace was galvanising; first the 20-year-old midfielder converted a penalty to give his side the lead, then he struck a sumptuous volley for Argentina's third in the 71st minute.
They did not look back, scoring twice more through Julian Alvarez and Adolfo Gaich while South Africa added one to their total late on courtesy of a Lyle Foster spot kick.