The Boks have been overrated for ages. Not saying they aren't one of the top teams, but they've never been "ahead of the pack", they have been very much in the pack since before the RWC. Their RWC win was reliant on us missing two very kickable penalties, despite playing 15 v 14 for the majority of the match. A team that was so far ahead of the pack would have won that game comfortably with the 1 man advantage.
I think this match is going to be close as hell. The Aussies are full of confidence, they were excellent against the best of the North and probably deserved to win that series, and after last weekends win they have nothing to lose. The Boks on the other hand have to try to revert to type as they got exposed badly, which doesn't tend to lead to them blowing teams off the park. And if Aus are still in the game with 15 to go... she's all on.