The Test at Ausgrid Stadium is scheduled on the Tuesday night, immediately after a round of Super Rugby, so Deans will now announce his team on the Sunday to ensure the fitness of all players is properly assessed.
With the Queensland Reds and Western Force enjoying round 15 byes, combined with a Brisbane Test against Wales to follow on June 9, Deans has indicated he'll rely heavily on Reds and Force players to play the struggling Scots.
The three-man Australian selection panel will name a train-on squad of Reds and Force players on May 28, when they will also go into camp in Sydney.
The Melbourne Rebels host the Brumbies on Friday, June 1 while the NSW Waratahs meet the Hurricanes in Sydney a night later, making it hard for usual Test incumbents to back up and play three matches in a week.
The Wallabies 22-man line-up to play Scotland will be deferred a day until Sunday so the selectors can weigh up injuries and fitness issues before finalising their combinations.
With Australia suffering a shock loss to Samoa last year after fielding a weakened side, Deans said the delay was designed to ensure he picks "a strong combination capable of winning what will be a tough Test match".
The Wallabies coach also hasn't forgotten Australia's last-start 9-8 loss to the Scots at Murrayfield in 2009.
"While Scotland is coming off a disappointing Six Nations, they are a team that has traditionally punched above their weight internationally, especially when under-rated," he said.
"We experienced that three years ago in Edinburgh and will not be taking for granted the threat that they pose."
Winless during the Six Nations, Scotland named five new caps in their 28-man squad on Thursday, including exciting Dutch-born winger Tim Visser, who is ineligible for the Newcastle clash.
The Andy Robinson-coach Scots have been hit by injuries with No.8 David Denton (ankle), winger Lee Jones (shoulder) and flanker Kelly Brown (leg) all out, while lock Jim Hamilton was suspended and prop Allan Jacobsen rested.
Scotland: Backs: Joe Ansbro, Mike Blair, Tom Brown, Chris Cusiter, Nick De Luca, Max Evans, Alex Grove, Stuart Hogg, Greig Laidlaw, Sean Lamont, Matt Scott, Tim Visser, Duncan Weir. Forwards: John Barclay, Geoff Cross, Ross Ford (capt), Ryan Grant, Richie Gray, Dougie Hall, Robert Harley, Alastair Kellock, Scott Lawson, Euan Murray, Ross Rennie, Tom Ryder, Alasdair Strokosch, Richie Vernon, Jon Welsh.