their defence is bad, but their number1 goalkeeper who played against Argentina and germany, Mark Shwartzer is good, better than Mirzapour, put it that way !!!
They didn't play their full-strength side against Tunisia, thats why the lost !!! If they had played the same team against them, i am sure they would have won !!!
Plus Australia wasn't at full-stringth at this tournament, they still have kewell, Bresicano, Grella, Lazaridis and a fit Viduka( he still was injured) to come back !!! they just need to fix up their defence; its too old and they do too much ball watching !!!