Australia captain Michael Hooper is excited to see "outstanding" talent James O'Connor back in a Wallabies shirt as they take on Argentina on Saturday.

O'Connor has not played for his country since facing the Pumas in 2013, but he has been named among the replacements for this weekend's Rugby Championship clash in Brisbane.

The 44-cap international has already impressed Hooper in training, increasing anticipation of his return.

"His ability is outstanding," Hooper told a news conference of O'Connor. "I haven't seen him for quite a few years - obviously I've seen him play - but he's still got remarkable ability skill-wise, speed-wise.

"He's been able to show that in training, so it's really exciting for him to get an opportunity out on the field.

"James has been building himself within the group, taking things in, seeing where he can inject, things like that. He's been a really enjoyable player to have in the squad."

Christian Lealiifano will start, meanwhile, having returned to form with the Brumbies after a battle with leukaemia.

Hooper says it is Lealiifano's leadership that has impressed in Super Rugby, potentially giving Australia a boost in that department.

"Christian this year, from watching from afar and playing against him, has a really great leadership quality," the Wallabies skipper said.

"The way he drove the Brumbies around all year and the way they built momentum, they went close to a place that's really hard to win at.

"As a reward of really good performance and leadership, he gets his opportunity here, where he hasn't been in a couple of years. It's fantastic for him and his family."