Slightly weakened, Chile's high defensive line was exposed time and time again in a 3-2 friendly win against Egypt on Saturday. And it was pure pace and acceleration which did the job.
Much was made of Chile's performance in a 1-0 loss to Germany in March, particularly their ferocious pressing.
But, allowed to dominate the ball against weaker opposition, holes were evident and taken advantage of by Shawky Gharib's men.
From the outset, there was joy to be had in behind.
Chelsea attacker Mohamed Salah opened the scoring and Khaled Kamar also struck in a five-minute period in the first half.
There was nothing particularly attractive about the build-up, other than the ability of both to time their runs.
Gary Medel's turnover of possession in the middle third led to Salah getting in behind, while Kamar simply latched onto a well-weighted long pass from Ali Ghazal.
Chile captain and goalkeeper Claudio Bravo played the role of sweeper-keeper, but he was powerless thanks to Egypt's good execution.
Neither Tim Cahill nor Josh Kennedy have the pace to get in behind and break away, but it could be Adam Taggart's role to play if he makes the 23.
Mathew Leckie could do it, but he may also be needed to start on the right after his good display against South Africa.
Egypt defended relatively deep with numbers behind the ball, and it took Alexis Sanchez's brilliance to break them down.
He set up all three of Chile's goals, including Eduardo Vargas' second-half brace.
But Egypt's performance would have been a positive for the Socceroos, who are capable of playing in a similar way.
It may mean Postecoglou strays from the possession-based style he wants to implement, but Egypt were still entertaining to watch during their best periods in the first half.
Good luck to Jason Davidson, who is likely to start at left-back and look after Sanchez. The Barcelona attacker played mostly on the right, but the front four of Chile rotated well. He lost his marker often and, when allowed to turn, set up the second and third goals.
Vargas hurt his ankle after a heavy challenge and played on before coming off late in the second half.
Arturo Vidal, a major injury concern for Chile, played no part, but his addition appears much-needed in the middle of the park.
Pressing is clearly a key for Jorge Sampaoli's men, who were largely unthreatening with the ball until the second half and when Sanchez was involved.
If fit, Mark Bresciano has the ability to pick out the passes from deep Australia may need to get in behind.
Staying compact will be particularly important as Chile showed the class capable of opening up opposition defences.