The Wallabies are sweating on the fitness of David Pocock, who suffered a hand injury in the win over Argentina on Saturday night.
Pocock came off in the 35th minute with the injury, going for scans after the game to determine the damage.
Wallabies coach Michael Cheika said he wasn’t sure how Pocock had sustained the injury, with the extent of the injury likely to be confirmed on Sunday morning.
"He's got an injury to his hand. We'll just have to see to what extent it is,” he said.
“It was quite swollen, so it was hard for him to move his hand.
“We decided to take him off, thought Sean McMahon was ripe to go anyway.
“We'll see how that pans out after he gets an X Ray.”
Saturday’s match was Pocock’s last in Australia before a 2017 sabbatical from rugby and Cheika said the 28-year-old wanted to play through the injury but needed to come off.
“He wanted to play through but I had to take him off. Definitely wanted to play it through.”
Pocock’s poor fortune is the latest in an injury-affected career, with two consecutive knee reconstructions, ankle syndesmosis, a calf concern and an eye socket fracture ruling him out of matches.
The number eight was the only Wallaby with an injury concern coming out of the Pumas win, which was a crucial victory in a difficult 2016 for Australia.
Pocock was replaced by Sean McMahon in the match, with the 21-year-old making an immediate impact and crashing through a pack of players to set Will Genia up for his first Test double.
Cheika was full of praise for McMahon and the other bench players after the match, for the work they did in holding off the Pumas.
“It’s a big part of how we want to play with the finishers,” he said.
“That's where the game can be won or lost, a lot of these Test matches because they are usually pretty tight.
“The set up is done by one set of guys and the finishers have got to be part of the other.
“Sean McMahon was outstanding with a couple of carries, which got us on the front foot.
“And that's their role within the team, so once everyone knows their job really clearly and they go out and do it, it makes for a much better flow in the game for us.”