The Springboks currently top the table following those two wins and are now firm favourites to complete a clean sweep of home wins ahead of a tough three-match away leg in a competition they last won in 2004.
But vice-captain Matfield, who will win his 86th Test cap at Newlands, is taking nothing for granted against a Wallabies team eager to bounce back after they lost their opening fixture 22-16 to the All Blacks three weeks ago.
“Against the All Blacks, it was the little things that cost them and we all know how tough it is in New Zealand,” he said. “They were just off in that game, and they think they can win this weekend.
“You could say the break leaves them under-cooked, or you could say we are over-played.
The Bulls lock is also expecting a stronger line-out threat from the Australians than that posed by the New Zealanders and has singled out Nathan Sharpe as the major difference.
He continued: “Nathan Sharpe has been running their line-outs for a while now and they’ll definitely be a bigger challenge than the All Blacks.
“They also stole quite a bit of ball against them on their own ball and the All Blacks’ ball. It was tough that they lost, but the little things cost you games.
“In any of these Tri-Nations matches, any team can beat any other team. They played in New Zealand, and that’s tough.”
Matfield is set to net another one of his growing milestones in the green and gold when he and Bakkies Botha play together as a lock-pairing for the 50th time in a Test for the Springboks.
And it is something he is heartily looking forward to, adding: “Being with Bakkies every day in the team environment has been special.
“He’s a great guy to be around. We’ve done so many things together, World Cup, Currie Cup, Super 14 and Tri-Nations.
“We’ve got a job to do on Saturday. We have to deliver for the Boks in the same way we’ve been doing in the past.”
AFRICA: F Steyn; JP Pietersen, J Fourie, J de Villiers, B Habana; M Steyn, F du Preez; T Mtawarira, B du Plessis, J Smit (capt), B Botha, V Matfield, H Brussow, J Smith, P Spies.
Replacements: C Ralepelle, J du Plessis, A Bekker, D Rossouw, R Januarie, R Pienaar, A Jacobs.
AUSTRALIA: A Ashley-Cooper; L Turner, S Mortlock (capt), B Barnes, D Mitchell; M Giteau, L Burgess; W Palu, G Smith, R Brown; N Sharpe, J Horwill, A Baxter, S Moore, B Robinson.
Replacements: T Polota-Nau, B Alexander, D Mumm, D Pocock, W Genia, P Hynes, J O’Connor.