Bok coach Jacques Nienaber has moved away from what had been his preferred 6-2 split on the bench between forwards and backs, which brought sustained physical and mental pressure on opponents in the final 20 minutes of games.
A string of injuries to backline players in Tests this year has seen the team having to play players out of position with little cover among the replacements, which has resulted in a return in Saturday's Test for Frans Steyn, who can cover flyhalf, centre and fullback.
That may weaken the impact of the Bomb Squad - the bench replacements - in the forward battle in the closing stages against the Wallabies and perhaps lead to a change of game-plan away from the relentless pressure imposed by their pack, but replacement prop Koch does not see it as an issue.
"It doesn't have a massive impact, each one of the Bomb Squad has a certain role, so if it is a 6-2 split or 5-3, we all know what to do when we get onto the field," he told reporters on Wednesday.
"Once we get a chance to go on the pitch we just have to perform and keep the intensity where the starters left off.
"Australia has a really good pack and a good front row on the bench as well. It's going to be a challenge, but our focus is mainly on us and what we can do better.
"We have to deliver what we have trained, and it's going to be a nice battle and a good challenge for us."
The Boks are looking for their first win in Australia since 2013.
