Good looking team named by Australia. Only change I probably would have made is Simmons for Vickermann, as Simmons has a phenomenal work-rate (and a strong combination with Horwill, Samo et al.). I can understand entirely why Higginbotham doesn't make the bench - he is great in an open expansive game, but in a tight contest you want your forwards to be hitting the breakdown and doing their job in the tight, rather than standing on the wing waiting for the ball. I really like the look of Australia's backline with Ioane back on the wing (and AAC back at centre).
South Africa look to have an advantage up front, though Kepu and Alexander can hold their own at times. The lineout battle will be interesting - neither team has had an overly dominant lineout so far this RWC (both at 82% on their own throw). I think South Africa have a slight edge in the loose-forwards. Pocock vs Brussow will be a highlight - I rate Pocock as the best openside in world rugby, though Brussow is not far behind (alongside McCaw and Warburton). If it was simply a 1-on-1 battle at the breakdown I would give Pocock a slight edge, however I feel South Africa have an edge as Burger works exceptionally well in tandem with Brussow. Elsom and Samo do provide Australia with some running threats, but I expect Spies to cause Australia some issues off the back of a (reasonably) dominant South African pack.
Where Australia do have an edge is in the halves. Genia has been great, but Cooper has been pretty quiet this RWC. I think both Genia and Cooper could cause South Africa some big problems; Genia will look to snipe close to the ruck and take advantage of the poor lateral defense of some of the South African tight-forwards (J Du Plessis, Smit, and Rossouw in particular), while Cooper will look to exploit South Africa's rush defense by doubling around in mid-field - at tactic Samoa used effectively at times last week. Morne Steyn has played well so far this tournament, but du Preez still looks quite a long was from his best - if South Africa want to defend their RWC crown du Preez is really going to have to step up.
The midfield looks pretty even to me: de Villiers and Fourie are arguably a better attacking combo (though AAC has looked dangerous this tournament), however they certainly won't receive near as much ball as McCabe and AAC. McCabe and AAC are a very strong defensive duo - if anyone isn't sure why McCabe is in the team count he number of tackles he makes in the match (it will probably be between 10-15) and count the number he misses (it will probably be 0-1, most likely 0). I think Australia have a clear edge in the outside backs too: O'Connor, Ioane, and Beale are all deadly with space to move. I expect O'Coonor, Beale and Cooper will be tested a lot under the high-ball, but South Africa will have to make sure their chase is good, as Australia can be devastating on the counter-attack. Pieterson and Lambie have been pretty good for South Africa, but you can't help but think much of their role will involve defending, defusing bomb, and chasing kicks.
Overall I expect is to be a very close match. South Africa do have an edge in goal-kicking, though O'Connor can be a very good kicker... as long as he nails his first kick. If he misses his first kick he can end up having a shocker, which Australia can't afford. I'm picking Australia by 5, but I'm really not sure either way.