Scotland flanker Blair Cowan says the Dark Blues have never faced a bigger challenge that the one awaiting them at Twickenham on Sunday.
The Scots will march into London looking to claim a World Cup semi-final slot for the first time in 24 years.
But to take that giant next step they will have to fight off an Australia side which head coach Vern Cotter believes are favourites to go all the way.
However, London Irish back-rower Cowan - given a tournament reprieve when he was called in to replace the injured Grant Gilchrist after missing out on the original squad - insists he will not blink as he stares down the Wallabies.
He said: "I'm very aware that this is probably the biggest game of my life. At the same time I've got a job to do and processes I need to go through before the game and I want to stay on task for that.
"I don't know if this will define our careers because we've got some boys who've had amazing careers.
"But it could be the pinnacle for us a lot of us.
"It's something we've spoken about. It's a milestone we want to reach.
"We're aware of the size of this game and what it means to us and the people of Scotland. But I've learned to put all the emotion behind me and stay focused.
Scotland have only lost once in their last three duels with the Aussies but that has not stopped the bookmakers from heavily backing Michael Chieka's side, pricing them at 8/1 on.
However, Cowan said: "We are aware that everybody is writing us off but if you don't have self-belief that you can genuinely win then there's no point going out.
"We are very aware in the this squad how good we can be and on our day we can beat anyone.
"The drive and the emotion is there for us. We don't need to worry about extra motivation.
"Don't get me wrong I'm not saying we're going to go out there and pump them.
"We know the task at hand. Australia have grown into a very impressive side so it will be a huge mountain to climb.
"But we are capable of doing it if we execute and play to our full potential."
Having prepared himself to watch the World Cup from his living room after failing to secure a slot in Cotter's first-pick 31-man squad, Cowan is now tasked with the crucial job of giving Scotland momentum at the breakdown.
Paired with John Hardie - the man who effectively squeezed him out of the original travelling party - in a reshuffled back-row, the 29-year-old New Zealand-born forward has been selected for his pace on the ground as Cotter looks to snuff out Australia's ability to get quick ball to their dangerous backs.
So far the Wallabies have thrived in this aspect, largely thanks to the efforts of double openside duo Michael Hooper and David Pocock.
But with Pocock ruled out through injury, Scotland have at least been given something to cheer.
"From the couch to the cup is how I describe it," said Cowan as he reflected on his return to action.
"But I was always aware that we have a 31-man squad and with the tightest turn-arounds you'll ever have in rugby that there was a huge possibility I could get called in.
"It was massively disappointing to miss the original squad but the one thing I said to Vern was that I was only a phone call away if he needed me.
"Now I'm back it would have been nice to go up against one of the best in the world right now because Pocock is an exceptional player.
"He brings strength all around the park. It's a big loss for them but they have depth, so anybody that goes in there is going to pose us a big challenge."