Postecoglou said on Monday he planned to make at least two changes to the side that thumped Kuwait 4-1 in Friday's tournament opener in Melbourne.
One will be enforced because captain and midfield dynamo Mile Jedinak is sidelined by an ankle injury.
With three matches in nine days, Postecoglou is determined to keep his players fresh rather than rely on a core group, as he did at the 2014 FIFA World Cup, where it appeared the team may have been fatigued by the time of its final group B game against Spain.
"We've learnt pretty clearly at the World Cup by the third game against Spain we were pretty spent as a group because we relied on a core group of players," Postecoglou said.
"Not just for those games, but in the lead-up.
"We don't want to fall into the same trap. We want to do well in all three games and tomorrow night is a very, very important game for us.
"We do want to make sure the guys we put out there can maintain the sort of tempo and intensity we had in the first game."
He said tests had revealed no serious damage to Jedinak's left ankle, but he couldn't be sure the key midfielder would be right for Saturday's final group game against South Korea in Brisbane.
"He's no certainty for Saturday either at this stage, so we'll see how he recovers, but we're certainly fairly hopeful that he'll overcome it pretty quickly.' Postecoglou said.
"There's nothing major. We've had scans done, so there's nothing significant there. It's just a matter of letting the swelling settle down and getting back running."
Postecoglou reported no other injury issues and expected another tough game against Oman, which lost 1-0 to South Korea in its first group match.
