The Wallabies say winning is the No.1 priority, but Giteau and Moore's impending milestones add an extra layer to their do-or-die contest.

Just six other players – Adam Ashley-Cooper, George Gregan, George Smith, Nathan Sharpe, Stephen Larkham and David Campese – have played 100 Tests for Australia.

The Wallabies will try not to get caught up in the significance to ensure they don't underestimate Scotland.

"The main focus is winning the quarter-final and those guys [Moore and Giteau] will be the first to tell you that," said Wallabies vice-captain Michael Hooper. "I've been a part of Adam's 100 milestone and to get two guys doing it in the same week will be really exciting."

Most experts are predicting the Wallabies to cruise into the semi-finals by disposing of Scotland at Twickenham on Sunday (Monday morning AEDT).

But after winning two of the past three matches between the countries, Scotland go into the clash high on confidence and ready to shock the world.

Scotland admit they will be the underdogs, but prop Alasdair Dickinson is adamant they can "do something special" to cause a major upset.

"We have got to go out there and impose ourselves on the game. It's going to take a huge performance from us, there's no doubt about that. But there's no reason why we can't go out there and do something special," Dickinson said.

"I'd say from this World Cup, they are the form team so far, definitely. They were outstanding against England and showed how clinical they can be in that Wales match. It's going to be a huge test for us.

"There is no doubt we are going to be massive underdogs, but we can take confidence from they fact we've got out of a pretty tough group to reach the quarter-finals. We have nothing to lose. I don't think anybody expects Scotland to win this match."

The Wallabies showed remarkable defence to hold out Wales in a 15-6 thriller in the last pool match last weekend.

But their attack lacked the clinical edge to cause damage, with all of the Wallabies' points coming from Bernard Foley's boot.

Foley has scored 43 of Australia's 59 points in their past two matches and coach Michael Cheika conceded the attacking accuracy needed to improve.

Wales was willing to give away penalties to halt the Wallabies' attacking momentum and Scotland could adopt a similar approach to keep Giteau, Israel Folau, Drew Mitchell and Tevita Kuridrani out of the game.

The Wallabies made just four line breaks and got across the gain-line 26 times in 80 minutes.

"We had to do different things [against Wales], we didn't have enough flow and I think there's a lot of improvement left in our game around the attacking parts from a consistency point of view," Cheika said.

"Every time we got into a ruck situation, they were getting penalised. So it stunts your attack and … we weren't getting the crisp ball [from our lineout] to launch the attack. It's another big area for improvement for us."

WORLD CUP QUARTER-FINALS

Quarter-final one: South Africa v Wales at Twickenham, 2am Sunday AEDT.

Quarter-final two: New Zealand v France at Cardiff, 6am Sunday AEDT.

Quarter-final three: Ireland v Argentina at Cardiff, 11pm Sunday AEDT.

Quarter-final four: Australia v Scotland at Twickenham, 2am Monday AEDT.