Looking to avenge last year's four-point loss to the Pumas at the same venue, the Australians started brightly enough.
But they lost inside centre Matt Toomua after eight minutes when he took a heavy hit tackling his opposite Juan Pablo Socino and was unable to return after failing the concussion test.
Wallabies coach Michael Cheika made the unusual decision to replace him with Quade Cooper rather than Kurtley Beale, who played there all Super Rugby season.
While they scored a try through Joe Tomane soon after, their attack lost shape without hard-running Toomua.
Tomane's try came after Argentine five-eighth Nicolas Sanchez kicked the ball down the throat of Israel Folau, who ran freely before the ball found the winger on the charge.
Cooper's night hit a low in the 65th minute when he was yellow-carded after taking out Sanchez who had just kicked down-field.
His card brought the biggest cheer of the night from the Mendoza crowd, with their team unable to notch a try.
Lucky for Cooper, the only addition to the score in his absence was another Foley penalty.
The Wallabies held an 8-6 lead at halftime with Foley missing the conversion and a penalty but another two successful strikes early in the second half opened up a 14-6 buffer.
Lock Dean Mumm came off the bench to score an impressive second half try, running from outside the 22 and fending off the defence to touch down.
Tevita Kuridrani and Adam-Ashley Cooper then both crossed in the dying minutes to pick up a bonus point and seal the win.
-AAP
