Australia's 3rd goal is crucial as it's thrown out many possibilities. If UAE draw, they'll be on -1 GD while Australia are currently on 0. UAE reaching 0 would require a win, thus eliminating Vietnam, jumping Australia on points and Australia would then beat Japan on H2H.
Should Australia win 3:2 and UAE draw then it'll come down to GD amongst the 3 and Japan would be 2nd on +1. So Japan just need to lose by 1 should UAE draw to advance.