Celtic midfielder Tom Rogic was among the goals for Australia as they swept Vietnam aside to keep their World Cup hopes alive and kicking.
But they remain out of the automatic qualification spots as it stands after fellow Parkhead star Daizen Maeda helped Japan to a crucial win over China.
The Socceroos had dropped points in each of their last three games prior to this international break and could scarcely afford to lose more ground in Melbourne on Thursday.
But there was no drama about it as former Hibs loanee Jamie Maclaren fired them into an early lead before Rogic struck on the stroke of half-time.
He was slipped through by Melbourne City's Matthew Leckie before dinking keeper Tan Truong Bui with a typically classy finish.
It set Australia on their way and further strikes from Craig Goodwin and former Hoops target Riley McGree secured a comfortable 4-0 win.
The Aussies are in qualification Group B alongside Japan and the win temporarily moved them into second place.
But Japan, who kicked off an hour later, soon reclaimed their spot as they held Australia at arm's length.
A 2-0 win was enough for them and Maeda emerged from the bench for his first appearance since 2019 to help them see it out.
Maeda has been in fine form for Celtic though insisted after his call-up that it came thanks to his stunning form for Yokohama F. Marinos - not his lightning start to life at Parkhead.
He was an unused substitute in November's internationals but he made a long-awaited return to the Japan side here - even if he was once again left waiting for his first goal.
He was the only of Celtic 's Japanese contingent to feature with Kyogo Furuhashi injured and neither of Reo Hatate or Yosuke Ideguchi selected.
The results mean Japan sit a point ahead of Australia in second, although both teams trail Saudi Arabia who remain in control of the group.
Japan have the chance to take top spot for themselves when they face the Saudis on Tuesday while Australia will hope to make up some ground against Oman.
And the two sides then meet on March 24 in a game that could effectively send one of them to the World Cup.
