Wellington - Rocky Elsom has said Australia must win the battle of the breakdown if they are to beat defending champions South Africa in their Rugby World Cup quarter-final on Sunday.Both teams have poachers’ extraordinaire in the shape of David Pocock, for the Wallabies, and Heinrich Brüssow for the Springboks.And Australia back-row Elsom, himself no mean player at the breakdown, said it would be a key aspect of the match."If you ever discount the breakdown, you're going to be in trouble, particularly as you get to the pointy end of the tournament," Elsom said on Tuesday."That's going to be a real area of contention because any time you get dominance at the breakdown you're going to provide front-foot ball for attack and that's an enormous part of the game."If you look at the teams whose attack has stuttered you can always link it back to the breakdown."Elsom added Sunday's match against Australia's old foes would be tactically and mentally different from a Tri-Nations match."The fact we're more familiar with them means we've got more background on them and we don't have to pore over as much footage, but by the same token we know they can be a handful and they're a very good side," he explained."You just need three big games (in the knockout phase). Win, draw or lose this weekend, you've got to start afresh."If you're going home, it's disappointing, but if you're going into the semis it's a totally new game in this tournament, more than any other."It is important to take lessons from the past. We don't have to go too far back to have a look at when we don't do things so well to see how it turns out for us,""One of the great things about Test matches are you really find out where you stand," said the 28-year-old Elsom, capped 73 times by Australia."We've got a tough opposition in South Africa and on Monday you'll have a clearer view of how world rugby sits."Elsom added that this tournament differed from the 2007 World Cup in France, when Australia were pipped in the quarter-final by England, who then went on to lose to the Springboks in the final."It's obvious the games are different. There's a whole lot more advantage in the defence," he said, in a view that differed from many pundits' perception of how rugby had changed in the past four years."The strength of the South African defence is that they get off the line very hard and it can be very good for them and it has been good for them so far."Utility back Adam Ashley-Cooper said Australia, stunningly beaten 15-6 by Ireland in the pool stages, had to raise their game and be ready to go the distance against South Africa."We're looking for a lift in intensity and urgency. We'll approach it like it's our last game, because if we don't get past it we're going home on Sunday."All the games played (at the tournament) show the 80-minute effort is important."