Australia maul Argentina with big win in Mendoza but Cooper a big injury concern

"We think it's an Achilles," Wallabies coach Dave Rennie told reporters after the game. "We'll get a little clarity around that, but it looks pretty serious."

Rennie, though, remains confident the Wallabies have talented options in reserve in the flyhalf position to overcome the loss of the Japan-based Cooper.

"We've got James (O'Connor) and we've got Noah (Lolesio), so we've got a lot of depth in that position and that's the good thing about this group," said Rennie.

"We've got a lot of guys on the injured list but other guys step up and front up. Again, we won't look for excuses around that. The next guy who steps up has got to front for the jersey and the country."

Argentina led 19-10 at halftime but Australia were much the better side in the second half as they got their driving maul going and scored tries through wing Jordan Petaia, loose-forward Fraser McReight, hooker Folau Fainga’a and centre Len Ikitau, to go with a penalty try.

Renner was impressed with his side's second half display, praising the "character and courage".

"We created opportunities first up and we didn’t take them, but I thought we were far more clinical (in the second half), applied far more pressure, and I think it was 10 penalties in a row at one stage in our favour, so I’m really happy with way we finished," Rennie told reporters.

"We’ve got more in us, but I’m really happy with the character. We had a couple of late changes and (we lost) a key guy in the game, but that’s the thing about this group. They have a lot of character and courage and they stood up."

As has been the case so often in the past, Argentina were let down by their discipline as they gave away a raft of penalties in the second period having managed tries through loose-forwards Pablo Matera and Juan Martin Gonzalez.

The welcome win in the Rugby Championship comes at the end of a difficult 24 hours for coach Dave Rennie’s side, who lost captain Michael Hooper on Friday when the latter opted to return home to Australia, suggesting he was not in the right frame of mind to play the game.

"It was tough. I felt like most of the game we were behind," stand-in captain James Slipper said. "It’s a real proud moment for me and for the team, because we really wanted to put in an effort that our fans could be proud of, but also that our captain, Hoops, could be proud of.

"We were thinking about him all day and we were playing for him tonight."

Concerning Rennie now will be the severity of the injury to the mercurial Cooper, who was seen wearing a moon boot on the sidelines after he twisted his ankle early in the second half and had to be helped from the field.

He will be a major doubt for the second clash between the teams in San Juan on August 13th, where Australia will be confident of another win after identifying a weakness in the Argentine defence with their driving maul, which they used with devastating effect.

The game started well enough for the home side as Matera crossed for a well-worked try. The teams traded penalties after that, before Australia coasted through the home defence as a series of simple passes allowed Petaia to beat one defender and score.

Despite the fact that they trailed by nine points at the break, Australia looked dangerous each time they took the ball through the phases and after turning down an easy three points, scored a second try with a maul from an attacking lineout as Hooper’s replacement McReight crossed.

Argentina’s chaotic style saw them hit back with a brilliant score as they launched a counter-attack from their own 22 that was finished by Gonzalez.

The see-saw nature of the contest continued as Australia were awarded a penalty try when Argentina illegally tried to stop a driving maul and lock Matias Alemanno was yellow carded to compound their misery.

That proved the turning point and the visitors hit the front for the first time in the game on 65 minutes as Argentina continued to give away cheap penalties and Reece Hodge made the score 27-26 to Australia.

The win was sealed with another try from a driving maul for Fainga’a and a score after the hooter by Ikitau.