Australia is growing in confidence that it will be back to full strength for Sunday's Rugby World Cup semifinal against Argentina after getting better news on its injured players.

David Pocock, No. 8, whose presence at the breakdown was badly missed in last weekend's heart-pounding 35-34 victory over Scotland, is making steady progress from a calf injury he suffered in the final pool match against Wales.

Pocock has still not taken part in full-contact training, but Wallabies coach Michael Cheika expects him to be fit to tackle the Pumas.

"He's moving along really nicely as well because he's run already," Cheika told a news conference on Tuesday.

"We're really pleased with that, that's a good sign.

"We won't bring him back and say ′come into training lad and do everything' just progress him through. I'm really positive about him playing."

Cheika is also confident fullback Israel Folau, who missed the Scotland match with an ankle injury, will be back while he was more upbeat about the prospects of loosehead prop Scott Sio, who hurt his elbow against the Scots.

The 24-year-old underwent scans on Monday and the early diagnosis is encouraging, which could be good news for the Wallabies knowing that Argentina will really test them in the scrum.

"Scott Sio is moving along OK. We'll need a couple of days to check him out but we're really happy with the way he's come up today," Cheika said.

"The scan showed it wasn't as bad as it could have been, so he's moving along nicely."

The Wallabies are expected to announce their team on Friday.

The return of the Pocock would be a huge boost for Australia after its last-gasp escape against Scotland.

The Zimbabwean-born loose forward has been one of the star players at the World Cup, with his ability to create turnovers and control the ball in the mauls.

"We definitely needed someone over the ball probably a bit stronger especially in the defensive side of things, too," replacement flanker Sean McMahon said.

"Just to retain a bit of ball and get some back off them because Scotland did really well to get good ball running and good advantage line.

"We definitely needed a bit of ball in that area."