"We've beaten Australia before,” he said.
“I think not having that burden to overcome as well and little things like that help a little bit more.
“Australia are probably the best in the tournament so far and we are looking to end that on Sunday."
Scotland has made four changes to their side for the clash, including the forced withdrawal of Jonny Gray and Ross Ford (suspension).
The pair will appeal their three-week penalties on Saturday morning but Scotland coach Vern Cotter said the side needed to move on from the loss of the two.
"We are used to those things and we have to adapt and move on,” he said.
“These are things that we anticipate, though we don’t like them. These are situations we are used to and prepare for."
Cotter said Scotland would be prepared for a full 80-minute effort against the fast-finishing Wallabies, whose win over Wales was clinched in the final 20 minutes with some crucial bench injections.
"They haven’t lost a game yet, so they are the form team and the favourites not only to beat us but to go on and win the World Cup,” he said.
“They are a team that is more dangerous at the end, so we can't even allow a slight slip in concentration."
"You have to stop them stringing together phases of play and building momentum.
"They have strong individuals across the park. They are quick to the breakdown and very aggressive at the breakdown."