There are a number of factors that may suggest there's a chance Australia won't be as hot tonight, or at least will take a little longer to get going. PNG's lack of a kicking game will see them struggle to score any points at all, but I think a determined PNG defence and the chance of a more relaxed attacking effort from Australia might see the game go through the motions early on until PNG simply can't hold on anymore.
But if Australia stay true to form, well, how many tries can you fit into 80 minutes?