Asia Cup destroyer Thon Maker wants the Boomers to be more ruthless after the defending champions escaped some nervous moments to book a semi-final date with New Zealand.
Australia always led in their 99-85 quarter-final defeat of Japan in Jakarta on Thursday night.
But some incredible fourth-quarter shooting from Keisei Tominaga (33 points) created anxiety as Japan reduced a 21-point deficit to nine.
Tominaga nailed eight three pointers - one from the centre-court logo - and had another rim out that would have cut the lead to six with three minutes to play.
Maker (21 points, 13 rebounds, five assists) continued his fine tournament with another player of the game gong though as the Boomers exploited their size difference to progress.
It set up a final-four clash with the Tall Blacks, who beat Korea 88-78 in the later quarter-final.
The winner of that will play the victor of Jordan and Lebanon in Sunday's final.
"It feels good, into the semis ... an ugly game but we'll take that," Maker said.
"We can't let teams back in once we get a big lead like that, but a win is a win."
New Zealand have been powered by point guard Flynn Cameron, who flirted with a triple double (22 points, nine rebounds, eight assists) in the win over Korea.