Even when the Wallabies were reduced to 13 men during the deciding Pool A game, the Welsh were unable to find a way past their resolute defence.
“They have a very solid line and their players defend like dogs," Scotland resource coach Nathan Hines told reporters on Tuesday. "England and Wales couldn’t find a way through it.”
Scotland ran in three tries against Samoa, including a typical sniping effort from scrumhalf Greig Laidlaw to seal victory, and the pace of fullback Stuart Hogg and power of centre Mark Bennett could cause Australia problems.
"We’ve got a lot of belief and the general team spirit is brilliant," winger Sean Lamont said.
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"Of course we will be the underdogs. But Scotland relish being the underdogs. You can take us for granted all you want, and you’ll get bitten."
Back-rowers Michael Hooper and David Pocock are key to the Australian game plan and they will be reunited at the back of the scrum on Sunday after Hooper missed the Wales game through suspension.
“They are very good, that is why they run with two sevens," Hines said. "A part of rugby is to slow ball down and get as many turnovers as you can, and that is what those guys do.”
Scotland could be without hooker Ross Ford and lock Jonny Gray, who have both been cited after the 36-33 Pool B win over Samoa that sent them through to the last eight.
“It is not something we want, they are vital members of a 31-man squad and we don’t want to lose any members for whatever reason,” winger Tommy Seymour said.
“We are playing a team that have played some of the best rugby in the competition so far."
Scotland know that they will have to raise their game after making hard work of seeing off Samoa.
“It wasn’t the way we wanted to beat Samoa and we weren’t at the races for a large proportion of that game, but we showed great character to win," Seymour said.
"The belief is there now in the squad. Winning narrow matches like that creates a psyche where you are aware of what you have to do to win tight games.”
(Reporting by Ed Osmond; Editing by David Goodman)
