The All Blacks may return from Europe feeling the biggest threat at the World Cup won't be a specific opponent but a generic ploy. The rolling maul could end up killing their dream as everyone from up north and the Boks are so darned good at doing it.
The All Blacks must feel at times like every serious nation but them got a memo about the rolling maul: how to do it and when to do it kind of thing. A handy little all-you-need-to-know pamphlet.
What the test against England did was provide a sharp reminder that rugby in Europe dances to a different beat. It's not worse, or better - it just tends to have the emphasis placed on different areas.
The means by which most teams look to exert pressure is usually through their physicality first, creativity second. Whereas in New Zealand it is the other way around.
The respective means are equally legitimate and while there will probably always be a slightly sneering view of Northern Hemisphere game plans held by their southern counterparts, what England showed at Twickenham was their unquestionable potential to crush teams with their rolling maul.
The Scots will no doubt try it at Murrayfield, as will the Welsh, because when it is done well, the rolling maul is a phenomenally successful device.
It is entirely contrary to the ethos of the game of having a fair and open contest for the ball and it doesn't feel like the defending team has any real rights to do much about it legally.
But the rules are the rules and fair play to the likes of England who know it's value and have come close to perfecting the business of sticking the ball up their jumpers and slowly marching down the field with it.
The All Blacks didn't defend well against it at Twickenham and, as a consequence, the home side were able to not only make territorial gain from it, they used the rolling maul to slow the game down and frustrate the All Blacks.
It was smart and it was worrying as it wasn't so hard to wind the clock forward and see not just England, but Ireland, France or South Africa enjoying similar success with the rolling maul against the All Blacks at the World Cup.
"With the rain coming down pretty heavy they tightened it up a bit and they showed they can play that way," said All Black lock Sam Whitelock.
"That [rolling maul] is something they are really good at. That is something we have to improve upon in our own game and make sure that if we do come up against them next year or future years we can stop it and stop it early rather than let it flow on. They gained confidence from it."