Giant lock Will Skelton believes Scotland will prove Australia's toughest test yet as they continue their bid for a Grand Slam at Murrayfield on Sunday.

The Wallabies are on course to emulate the 1984 Australia team who swept past the four home nations, but after beating England and Wales they must overcome Scotland on Sunday and Ireland next week if they are to match the feat of 40 years ago.

Wins at Twickenham and Cardiff have sparked a revival after Australia finished bottom of the Rugby Championship standings in September with five losses from six matches.

"I've been with the group like two and a half weeks now and we're showing how connected we are, we've got a good buzz in the group and we're really focused on this week and excited about the challenge to play Scotland," Skelton said on Wednesday.

"We were always building, when you have losses, there's lessons to learn and this group is strong enough and is led well enough to get out of those holes," he added.

"The test against Scotland is going to be the hardest one yet so we're excited about this week and we're looking forward to ripping in."

Skelton also warned of the threat of Scotland's backs.

"You've got a guy like Finn Russell who's a maestro at the back there. I think it's going be a close one and we'll be up for it," he said.

"There's some class players in the Scottish team and when they're at it they're world class."