Former South Africa captain Bobby Skinstad insists the Springboks' only hope of claiming a place in the World Cup final is by "out-smashing" old foes New Zealand.

A heavyweight last-four showdown between the two southern hemisphere giants looms at Twickenham on Saturday with the great rivals set to clash for the 91st time, the All Blacks winning on 52 previous occasions.

South Africa have rebuilt since their stunning defeat by Japan on the opening weekend, culminating in a nail-biting quarter-final victory over Wales, while New Zealand were outstanding in routing France at the same stage.

Skinstad, who won 42 caps until his retirement after the 2007 World Cup triumph, believes that only by elevating their trademark power game to a new level can the Springboks prevail.

"Out-smashing the All Blacks is the only way we can beat the All Blacks. We can't out-run them," Skinstad said.

"The only way we can win is traditional powerhouse South African rugby and the players will not need to be psyched up for that, they will be really excited about this game.

"They'll love the clash and will want to smash into the All Blacks. More than anything, they'll just be pleased to have a chance to do that.

"We have to go really hard in the forwards for a long time before we can look to go wide. The All Blacks will go wide earlier than us.

"It's going to be a massive clash. If The Springboks are on song they'll be in with a shout.

"South Africa will be thinking 'we've pushed the All Blacks close before, so let's prepare for fire and brimstone. Let's take them on and march on to the goal'.

"New Zealand looked special against France, but France let them play like that. Maybe they've laid their World Cup bogey against French teams to rest now.

"But New Zealand are also a southern hemisphere side that we see a lot of.

"We play them twice a year so they won't be able to outfox the Springboks as easily as they did the French, but they're still a powerful team."

Schalk Burger was man of the match in the 23-19 victory over Wales but unusually for an openside, spent most of the match operating at first receiver. He received rave reviews, but Skinstad was less impressed.

"I know Schalk and I love Schalk. He's a fantastic player but for me he's standing at first receiver too much," Skinstad said.

"You can't begrudge him the number of contributions he's made, but it's about the quality of those contributions.

"Did he off-load to somebody who ran through a gap? Did he lose the ball on the ground?

"He's playing well but against New Zealand he needs to carry less and tackle more. He needs to do the hard yards, clean out more.

"Schalk is a great contributor but he needs to spend less time at fly-half if South Africa are going to win."