Elsom and co lost the battle of the breakdown when they were beaten by Ireland a fortnight ago and the former Leinster star knows a similar showing against South Africa will lead to a premature exit from the seventh global gathering.
"If you ever discount the breakdown you are going to be in trouble, particularly as we get to the pointy end of the tournament," said Elsom.
"That is going to be an area of contention, because any team that gets the dominance at the breakdown are going to provide front-foot ball for their attack, and that is an enormous part of the game.
"I think if you look at the teams whose attack has really stuttered in this tournament, you can almost always link it back to the breakdown.
"Obviously, the game flows in the pool stages when you have lesser sides versus more fancied sides, but in the big games it tends to tighten up and every inch of ascendancy you can gain there at the breakdown is crucial."
Australia were without star openside David Pocock when they were shocked by the Irish and his presence against a Bok pack that will include renowned scavenger Heinrich Brussow will be of massive importance to the Wallabies.
That defeat to Brian O'Driscoll and co was as big a shock as their loss to England in Marseilles four years ago - a result that saw the Wallabies knocked out of the World Cup at the quarter-final stage. And although a first Tri Nations crown in a decade was secured earlier this year thanks in part to home and away wins over the Boks, embarrassing defeats to Samoa, Scotland and England over recent seasons have reminded Elsom that he and his team-mates will have to be at their best this weekend.
"It is important to take the lessons of the past, now and then," added Elsom.
"And we don't have to go too far back to have a look at when we don't do things so well how it turns out for us.
"It is just about the whole group being aware of what helps us go well, and in particular that this team performs well."