The Pumas had the running of the first half and led 19-10 at the break, courtesy of some poor discipline from the visitors, who conceded nine penalties in the opening 40 minutes.
But the Wallabies rallied, and scored three tries in the second half to surge home. Leading by 27-26 in the 70th minute, the Wallabies boldly went to the corner again and Folau Fainga’a did what he does so often in Canberra and pounced over. A try to Len Ikitau after the siren sealed the victory.
Cooper appeared to tear a calf muscle in the 47th minute, when pushing off to try and launch an attack. It seems likely he will be sidelined for a good portion of The Rugby Championship, if not all of it.
Fraser McReight, stepping in for Hooper, did his captain and the jersey proud with a busy performance that included a try.
Argentina led 19-10 after a first half often punctuated by the shrill whistle of the referee.
The Wallabies’ tendency against England last month to make life tough for themselves in their own half continued right from the start, when two errors gave the ball to the Pumas in the 22 in the opening minute.
They escaped that time but Pablo Matera didn’t take much longer to open the scoring, when he took a nice inside ball from about 10 metres out and beat the cover defence of Allan Ala’alatoa to score first points in the fifth minute.
The Wallabies responded with a penalty to Cooper from the kick-off, via some strong defence, but they gave the three points back straight away by infringing from the restart.
Australia were unable to mount any serious pressure because they kept turning over the ball, and with Adamson cracking down on offsides, the Wallabies were pinged again for another three points in the 15th minute.
The Pumas led 13-3 but they got back into the game with a bold decision to turn down easy points in the 16th minute. A lineout maul came to nothing but Cooper did enough on the next phase to draw in two defenders and give Jordan Petaia an angled run to the line for a try.
But the penalties kept coming, Argentina kicker Emiliano Boffelli banging over another in the 20th minute.
Cooper had the chance to put on a second try soon after when he made a clean break upfield but he failed to pass to a flying Fraser McReight in support, who would have likely scored. Another chance went begging soon after when James Slipper couldn’t hold a Cooper offload near the line.
A rough penalty against Jed Holloway ended the half, and Boffelli kicked another goal to extend the lead.
Holloway went close to scoring after Tom Wright counter-attacked well, but he had no support in the cleanout and the ball was lost.
Cooper was searching for another try in Pumas territory in the 47th minute when he slipped on some wet grass as he pushed off, and he immediately hit the deck clutching his calf.
Players consoled him before he limped off, seemingly aware it was a serious tear.
The Wallabies’ moods turned quickly, though, when they used a lineout maul near the line to score a second try. McReight burst through the middle to finally jag his first Test five-pointer.
The game and scoreline tightened up but the Pumas eased away again in the 55th minute when a sloppy kick chase allowed the hosts to fracture the chase line, and an 80-metre move ended with Juan Martin Gonzalez scoring a well-received try.
The game still had plenty of twists to come, though. The Wallabies again went into Pumas territory and used the rolling maul, and this time the referee pinged Argentina for illegally collapsing, and awarded a penalty try.
A long-range penalty from Reece Hodge finally took the Wallabies to the lead for the first time in the 64th minute.