I think Australia has to be careful here. While they are well and truly on top, things can slip away easily. If South Africa can get one good session without losing a wicket, they might be close to Australia's score by the end of play today. The Australian bowlers just don't look like taking wickets - Siddle with a strike rate of 100, Hauritz almost 90.
If South Africa needs 250 on the last day, I can see Smith coming in to bat, a broken finger is not going to stop him, I think South Africa is taking this test very seriously because a whitewash will mean so much more than a series victory.
As Harris said after the day's play - they will be going for the win and they won't be playing negative cricket.
I hope South Africa can pull this one off, but I would rather see them try to win and lose than playing negative cricket.