Billy Vunipola struck a defiant tone ahead of England's Rugby World Cup final with South Africa, telling the Springboks to "bring it on".

His words came after Lood de Jager promised the underdogs would "fight fire with fire" in what the towering South African lock expects to be a bruising encounter in Yokohama on Saturday.

Rassie Erasmus' men produced a gritty display to edge out Wales 19-16 in their semi-final, while England claimed a far more eye-catching 19-7 defeat of reigning champions New Zealand.

But the physical battle will be intense this weekend and Vunipola insists Eddie Jones' side are ready for it.

"They have already come out and said they want to fight fire with fire. I guess we return it by saying, 'bring it on'," said the number eight.

"They are very, very big people but then again we have a few big blokes on our team."

Vunipola revealed the bold approach England took in the semi-final inspired him, with Jones' men combining free-flowing rugby with a controlled aggression that rattled the All Blacks.

"It's something that you probably can't measure, but I think the best way to explain it is that it's quite contagious," he said.

"It shows everyone it can be done, so everyone else tries to follow in the slipstreams of [Sam] Underhill, [Tom] Curry, [Maro] Itoje.

"It's very easy when you see it. A lot of people talk about it and it's easy to sit here and say we want to be brutal, but you have to back those words up."

Vunipola faces a tough fight of his own against opposite number Duane Vermeulen, having ended up on the losing side three times against him.

"He's such a big player for them," Vunipola said. "I played against him last summer and he was monumental in terms of getting them those two victories [in a series the Springboks won 2-1].

"Not just myself, but we've got to try and negate the influence of him and everyone else around him."