Australia sit third in Group B of Asian qualifying after their 1-1 draw against Iraq, three points adrift of leaders Saudi Arabia and Japan.
Only the top two are guaranteed qualification for Russia and with four games remaining, Australia's hopes of a fourth straight World Cup appearance could hinge on the outcome of the meeting at Sydney Football Stadium.
"It's no bigger than last Thursday was," Postecoglou told reporters on Monday, referring to the draw with Iraq in Tehran last week.
"Obviously it's a World Cup qualifier and we've kind of set up an environment where we prepare for each game the same way and this is no different.
"If we win tomorrow night, it doesn't make the Saudi Arabia game (on June 8) less important, if we don't win, it doesn't make it more important.
"I think we're still, in terms of qualifying, where we know that our fate's in our own hands," added Postecoglou, whose side have laboured to four consecutive draws and struggled to score.
"We'll only start looking at other things if that gets out of our control."
The UAE sit just one point behind Australia after losing to Japan last week. The third placed team in each of Asia's two qualifying groups goes into a playoff.
Vahid Halilhodzic's Japan host Thailand at Saitama Stadium and will be expected to collect three points, while Bert van Marwijk's Saudi Arabia play an Iraq side in Jeddah that have picked up just four points from their first six games.
In Group A, leaders Iran take on a resurgent China and seek a win that could put Carlos Queiroz and his team just one victory away from securing back-to-back appearances at the World Cup finals for the first time in the nation's history.
Queiroz's side are four points clear of second-placed South Korea, who lost to China last week.
China are fifth on five points and their hopes of qualifying remain slim.
South Korea will hope to bounce back with victory over fourth-placed Syria, who handed Uzbekistan a 1-0 defeat last week to maintain their ambitions of qualifying for the first time ever.
The third-placed Uzbeks take on lowly 2022 World Cup hosts Qatar and need a win to reignite their challenge which has stalled after starting with back-to-back wins.
(Editing by Ian Ransom)
