Horne's tournament is in serious doubt after he left Twickenham with his left arm in a sling following a suspected dislocated shoulder in the Wallabies' rousing 33-13 win against England on Saturday night (Sunday morning AEDT).

Cheika has declared it will be full steam ahead for his team for the rest of the tournament, revealing he won't rest players in the last pool match against Wales on the weekend despite being guaranteed a quarter-final spot.

Horne had scans to determine how bad the damage was and Cheika must decide whether it is worth carrying Horne in the 31-man squad until he is fit again or whether it's best to bring an immediate replacement.

Scans showed the injury was not as bad as first thought and the Wallabies are investigating all possible option to keep Horne involved in the squad.

But it was Horne's commitment and courage against England which typified his career.

Horne fell awkwardly when trying to make a tackle with England on the attack. He was clearly struggling and his arm was limp, but he got back up into the defensive line and was ready to put his body on the line if needed.

"That's one of the reasons why Rob Horne is a pretty consistent selection," Cheika said.

"He brings a certain type of commitment and grunt that we are really asking our players to give. When you speak to him he's going, 'don't worry, I'll be right' and he's sitting there in a sling waiting to go for a scan.

"That's what we want from our players, we want them committed to the cause. I think they are."

Fullback Israel Folau (ankle) and inside centre Matt Giteau (sternum) are both expected to be fit to play against Wales after picking up niggling injuries in the dominant win against England.

Cheika has plenty of wing options in his squad with Kurtley Beale filling the void brilliantly for 70 minutes against England.

Australia's most prolific World Cup try-scorer Drew Mitchell, Henry Speight and Joseph Tomane are also options.

Cheika could opt to call up playmaker Christian Lealiifano, who can cover a variety of positions, or add another winger, likely to be Nick Cummins or Taqele Naiyaravoro.

The other option Cheika has is to call in a third halfback, most likely Nic White, as cover from Will Genia and Nick Phipps.

Cheika has rotated all of his players in the first three matches of the World Cup, but he says the time for experimentation is over and it's time to ensure his starting XV is battle hardened for the pointy end of the tournament.

Wales counterpart Warren Gatland has also said he won't rest players despite both teams already earning their place in the last eight of the tournament.

"There's no resting ... Everyone has had an opportunity there to rotate through and participate early on and get involved," Cheika said.

"We have to look at the collective load now, and say realistically we had the Rugby Championship and for the guys who started yesterday, they have really only played two matches in five to six weeks.

"You have to manage other things later on but right now I don't feel we have to be looking for rests and stuff like that.

"We have got to be working hard and getting that under our belt so we can profit from being body hard at the end of the tournament.

"I think we can do a bit more. We still have time to grow into it. That's how we tried to time it. But it is going to come down to the correct work, and real application."