Wallabies winger Rob Horne has made a miraculous recovery from a serious shoulder complaint to return to training ahead of Australia's Rugby World Cup quarterfinal against Scotland, but doubts remain over Israel Folau and David Pocock.

Horne, one of the team's toughest competitors and a renowned defensive threat, did contact drills during Wednesday's training session and acquitted himself well. His presence stunned the team's coaching staff who had not banked on him being fit so soon after dislocating his shoulder 10 minutes into the Wallabies' thrashing of England a fortnight ago.

Michael Cheika is not expected to rush Horne back into the starting line-up, with Drew Mitchell tipped to hold his place on the left wing, but Horne will certainly apply pressure to the veteran should Australia progress to the final four.

"He's back in training, we're trying to see if he'll be available for this week's game," Cheika said. "He got into some contact [on Wednesday] and said he felt good, which is very positive because we probably didn't think he would. He'll jump in again on Friday and we'll make a decision from there.

"Rob Horne is desperate to be selected, and he's prepared to go through the pain to do it. I think if he's not right this week he will definitely be right going further."

Folau and Pocock once again sat out training, with ankle and calf complaints respectively, but Cheika remains hopeful that both will be available to train on Friday after Thursday's rest day.

Kurtley Beale has trained at full-back all week and will step into the starting line-up should Folau not recover, while Ben McCalman is expected to shadow Pocock at No.8. Vice-captain Michael Hooper will return from a one-game suspension, taking the No.7 jersey back off young gun Sean McMahon.