Tom Rogic's suspension has Arnold seriously considering picking two strikers for the last-eight clash, with Apostolos Giannou pushing for inclusion alongside Jamie Maclaren.
Jackson Irvine could be pushed forward against the host nation to fill Rogic's void but Arnold has indicated he's loath to remove the Hull City midfielder from the No.6 role he's been playing so far in the tournament.
The altered system is one Arnold is familiar with after playing two strikers in front of two No.10s regularly during his time in charge of Sydney FC in the A-League.
Giannou has made virtually every post a winner after his late call-up to the squad as an injury replacement for Martin Boyle.
The 28-year-old scored against Palestine and came off the bench again in Monday's round of 16 match against Uzbekistan to score one of Australia's four successful penalties as the Socceroos progressed via a shootout.
Australia's lack of penetration against packed defences looms as their biggest obstacle. with Giannou expecting Arnold and his coaching staff to uncover a solution.
"It could surprise the other teams, maybe they think we'll play a certain way and we'll play a different way," Giannou said of a potential change of formation.
"That's up to the coaching team and coaches to find the way. We're just there to execute what they tell us."
Arnold potentially opting for two strikers would suit Giannou, who is keen to dispel any opinion he's a one-dimensional target man.
"Actually I prefer to be the second striker in a game rather than the one who sits up there and waits but either way I'm happy," Giannou said.
"If I'm playing, I'm happy."
