It is their most important match in at least four years, but South Africa forward Duane Vermeulen is playing it cool ahead of the Rugby World Cup semi-final against holders New Zealand on Saturday.

The Springboks, then defending champions, bowed out of the 2011 tournament in a quarter-final loss to Australia and have not won the Southern Hemisphere's Rugby Championships in its current format. Their third and final Tri Nations win came in 2009.

There is huge significance on the outcome of the last-four showdown at Twickenham this weekend, a match the All Blacks will start as heavy favourites after they demolished France 62-13 to reach this stage.

But despite the scale of the task confronting South Africa and what is at stake, Vermeulen has been able to condense the eagerly anticipated contest into its simplest form.

"We are going to bash each other for 80 minutes and then enjoy a good chat and maybe a beer afterwards," he said.

Vermeulen has operated at number eight in all but one of his team's five matches at the tournament, with Schalk Burger moved to openside flanker following the shock loss to Japan in South Africa's Pool B opener.

With 33 caps to his name since making his Springboks debut in 2012, the 29-year-old Vermeulen and his team-mates are intimately acquainted with Steve Hansen's side, meaning there should be few surprises and only fine margins to separate the teams as they each bid to reach the final.

"This week is all mental," he said.

"We know exactly how New Zealand play and they know how we play. The coaches have sorted out the way they want the players to attack, defend. As a player now it just comes down to mental preparation."