The Australians have won five of their last six Test matches against the Springboks, stretching back to September 2009.
But Queensland lock Horwill said those results would be irrelevant when the teams stepped onto the turf at Wellington Regional Stadium this weekend.
"Everyone has spoken about the fact that this is different," Horwill said. "World Cups are different. It's a tournament. It's knockout. This is it.
"You can put all history behind you. This is a game we need to win. It's a quarter-final against the Springboks. It's a huge occasion."
Past results may be irrelevant but the game plan used to bring about those victories is certainly something the Wallabies will not be throwing away.
Horwill does not expect the expansive, counter-attacking nature of the backline to be reined in too much, with the likes of Will Genia, Quade Cooper, Kurtley Beale and Adam Ashley-Cooper given licence to play what is in front of them rather than to a prescriptive plan.
"We want our players to take opportunities when we see them. That's the way we've always been," the 26-year-old.
"If someone sees an opportunity they need to take it and make the most of it. It's the same with any game we play.
"But knowing this is a big stage and the intensity and pressure is going to step up another level, we understand that, and we'll prepare accordingly."
The South Africans have conceded just two tries in pool play - one each against Wales and Samoa - and Horwill said his team would need to make every points-scoring opportunity count on Sunday.
"They are a very good defensive team. We're aware of that and we have to make sure we take our opportunities when we get them," he said.
The Springboks came into the tournament lacking form after the majority of their players were rested in the early stages of the Tri Nations.
But they have gained momentum with each pool match during the past month and have a good track record when it comes to the knockout stages in World Cups.
Wallabies coaching co-ordinator David Nucifora felt Sunday's match would hinge on one or two moments in the game.
"The team that actually loses concentration for a split second on the weekend is going to be the team that's going home," he said.
"I don't think it will really come down to much more than that. There will be one or two opportunities to win this game on Sunday and the team that is up for it and ready to take those chances will be the one that is staying."
Nucifora confirmed winger Digby Ioane, who broke his thumb in the first pool match against Italy, was back in the selection mix.
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