The Kookaburras have survived a scare to open their Tokyo campaign with a victory.
The world's top ranked team trailed Japan 3-2 at half-time, the hosts determined to make a statement in the men's hockey competition.
Australia were below their best, but they were good enough to take control in the second half and secure a hard-fought 5-3 victory.
Australian coach Colin Batch was disappointed with aspects of his team's performance, but was pleased to see his players fight back for the win.
"We played into their tactics a little bit and assisted their counter-attack," Batch said.
"While we set out not to do that at the start of the game, we were not good in that second quarter.
"We learned a lot from it but I have to say good composure in the first quarter and a very good second half."
Albion Park's Blake Govers started the comeback with a lethal shot from a penalty corner, before goals to Aran Zalewski and Daniel Beale closed out the match.
The Kookaburras will have little time to celebrate the win, the side to face India on Sunday night. India defeated New Zealand 3-2 on Saturday.
It's a match goal-scorer Tim Brand said will prove another tough assignment.
"I think they play a pretty similar style (to Japan)," Brand said.
"They're fast, skilful and pretty crafty. They counter-attack a lot so I think we need to knuckle down our defence. I reckon we're always going to score goals so yeah, defence (must improve)."
Japan burst out of the gates, the hosts receiving the first attacking opportunity of the match through a fourth-minute penalty corner.
Australia held firm before eventually gaining the ascendancy.
Goals to Brand and Thomas Craig in quick succession put the side up 2-0 at the first intermission and it looked like the Kookaburras would run away with the game.
Japan had other ideas, a successful review for a penalty corner swinging the momentum and the complexion of the match.
What followed was six minutes of mayhem, the hosts scoring three goals to take an unlikely lead.
Australia switched off and Japan made them pay for a number of defensive errors.
The hosts had an early opportunity to extend the lead in the third quarter, however this time Australia held firm.
Eventually the Kookaburras drew a penalty corner after a sustained period of attack and drag-flick specialist Govers made no mistake.
Australia were good enough to close out the win, however they will have to be much improved as the tournament progresses.