It's pretty simple. We win last two games, then two out of Sydney, Brisbane or Melbourne (!) need to lose one game each for us to make the four and give Geelong a nervous breakdown.
We know that Brisbane or Melbourne have to lose one because they play each other. So if Collingwood can continue their form against Sydney, or the Saints can beat Sydney in Melbourne, the deal is done.
You can make a good case for finishing third, although it relies of the Saints and Carlton having wins they don't deserve, and there's even a wild way we can finish second, but I wouldn't lose sleep over it.
But, really, win their last two games and the boys would be unlucky not to make a QF.