Michael Cheika revealed that there is very little momentum gained following his side's domination of England last Saturday.
The Wallabies kicked the hosts out of the tournament in the pool stages for the first time in a Rugby World Cup, but coach Chieka insists that the result has little bearing on the crucial fixture against Wales on Saturday.
Cheika used the Rugby Championship as an example. Australia were brilliant during their win over New Zealand in Sydney in August, only to travel to Auckland seven days later and get beaten 41-13.
"We supposedly had momentum after we beat New Zealand in Sydney as well," revealed the former Waratahs coach.
"And then they put their boot to our backside. And that can happen if you are not on every day. We have to learn from those times.
"When people are happy the way you play and all around you the world is all good, you can't just settle for the good part. You have to be great. We weren't on that occasion.
"It will be more difficult because of the nature of the tournament. Every match is a step up. Wales have an excellent game with variation."
The winner of Saturday's clash will face an easier challenge in the quarter-finals, as the victor plays either Scotland or Japan. However, Cheika believes there are no easy games.
"I don't subscribe to the theory that if you win your group, you are going to get an easier run," he said.
"That is disrepecting the opposition and that is not what we are about. It is going to be a big game for us. It is going to be a massive battle and pretty painful.
"I want just to try to win every game. No team ever won the World Cup losing a game. We have to keep getting better in tournament play because other teams are improving."
Cheika is preparing for a hostile reception at Twickenham, where the Welsh supporters will bring plenty of sound.
"Wales are a team that back themselves a lot," he continued.
"Even though we are at Twickenham, I have been ambushed before by the opposition supporters going to a different ground. I know there will be plenty of Wales supporters there and they will make it their own ground. We will have to be consistently strong in the way we play the game over 80 minutes."