Listen to many observers and it seems there is one standout instruction to take on ahead of Saturday's title match between England and South Africa: Win the physical battle. "They are very, very big people but then again we have a few big blokes on our team," Vunipola said, relishing the challenge. "They have already come out and said they want to fight fire with fire.
"I guess we return it by saying, 'Bring it on.'" It's no surprise to hear the word "brutality" being bandied around before a match between these two rugby giants, and it was heard again Tuesday through the bullish Vunipola and England's defense coach, John Mitchell.
"What we do have, or what we are going to witness, are the two most powerful rugby teams in the world," Mitchell, former head coach of the New Zealand All Blacks, said. "They are strong, well-coached, and the gain line is going to be huge.
"Going back to our DNA, we feel it's really important to us as well." The English outmuscled New Zealand in the semifinals on Saturday, with Sam Underhill and Maro Itoje, in particular, landing some shuddering hits in the 19-7 win in Yokohama.
They might need to raise that physicality one more notch a week on against a Springbok team that has gone back to what it has traditionally been strong at in their proud history — a solid lineout, a big scrum, ferocious tackling and a good kicking game.
In training on Tuesday, England prop Kyle Sinckler was spotted boxing on the field with a trainer away from the main group. So what is the effect of dominating the kind of big collisions that are expected this weekend?
"It's something that you probably can't measure, but I think the best way to explain it is that it's quite contagious," Vunipola said. "It shows everyone it can be done, so everyone else tries to follow in the slipstreams of Underhill, (Tom) Curry, Maro.
"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, who is expected to start alongside his brother, prop Mako, has his own individual contest to take care of. He has come up against South Africa No. 8 Duane Vermeulen on three occasions in test rugby and lost every time.
That head-to-head record is in his mind this week. "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."
Mitchell said he didn't expect any of England's potential injury concerns — Jonny May (hamstring), Owen Farrell, and Sinckler (tight calf muscle) — to be ruled out of Saturday's match.
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Steve Douglas is at www.twitter.com/sdouglas80