One of the most courageous defensive efforts in Wallabies history earned the players no respite from Cheika's brutal regimen in the build up to a quarter-final showdown with Scotland on Sunday (Monday morning AEDT).

The only ones to escape were David Pocock (calf) and Israel Folau (ankle) as both are closely monitored and managed, but winger Rob Horne was a surprise inclusion in a remarkable recovery from a shoulder injury.

The Wallabies are still being praised for an outstanding defensive display, which saw them hold Wales scoreless despite playing with 13 men for a seven-minute period in the second half.

But Cheika used physicality to blow out any lingering self approval to reset the team's mentality for a do-or-die battle against Scotland at Twickenham.

"We trained hard today, got stuck in … we've still got to go through some pain at training and build into the tournament," Cheika said.

"I don't see any reason why we need to be peeling back now. You've got to be smart, we've had a fair few Test matches in a row, so we're trying to manage that right to keep the edge but not busting anyone.

"We feel like we've done good ground work in the build up to give us the ability to keep training. We feel like we can get more body hard, we feel like we haven't fulfilled our potential there yet."

Pocock and Folau are being monitored as both race the clock to be ready to play Scotland at Twickenham.

Ben McCalman looms as the man to come in for Pocock if he fails to recover in time while Kurtley Beale is on standby to replace Folau at fullback.

Folau is expected to be fit to take his place, but Horne has provided the back-line surprise just two weeks after his tournament almost ended in injury disaster.

Horne busted his shoulder when scrambling in defence in the opening 10 minutes of the pool match against England.

The partial dislocation threatened to end his World Cup and the Wallabies contemplated sending him home to recover.

But Horne was desperate to stay in camp and made an amazing return to training on Wednesday (Thursday morning AEDT) to revive his campaign.

Horne is unlikely to come into selection contention this week with Drew Mitchell holding down his spot on the wing, but could be a valuable addition if the Wallabies progress.

Cheika said it was an indication of the determination in the squad, with intense competition for spots and no one wanting to miss out on a potential World Cup-winning charge.

"Rob Horne is desperate to be selected, he's desperate to be picked and is prepared to go through the pain to do it," Cheika said.

"So they should [throw themselves into it] … what an opportunity to be involved in and you don't want to let it go. It's good to see the lads are identifying that's the case."

Cheika is also contemplating a lineout change, with Rob Simmons, Dean Mumm and Kane Douglas battling for the two starting lock positions.

The lineout failed to deliver clean ball last weekend against Wales and the Wallabies' back line suffered via a lack of early possession.

The Wallabies were superb in defence against Wales and have only leaked two tries in the World Cup so far.

It would be easy to gloss over some of their deficiencies, but Cheika has identified aggression when carrying the ball as one of the biggest areas that needs improvement.Wales succeeded in slowing down the Wallabies' rhythm by either giving away penalties at the breakdown or holding players up in tackles.

Scotland will almost certainly use the same tactics to stop the Wallabies getting a roll on.

"When you're carrying the ball, you want to take advantage of it. We've taken some steps this week to try to get lower … to get aggressive in that part of the game to make sure we're not letting opposition defenders take advantage of us," Cheika said.

"At the end of the day, if your ball carrier is good enough and your ruck is good enough, then it won't happen. We need to improve that part of our game so those guys don't get in and we don't let guys into that zone regardless whether they're legal or not."