The All Blacks simply can’t surrender the cup to a team that's happy with a 50cm head of beer foam on a 37cm pot.
Aussies don't know how to pour beer. And under no circumstances can they be allowed to make off with our mighty vessel.
Those are the two major conclusions from a deep throat Herald investigation into the Bledisloe Cup.
The Herald has uncovered a damning article from 2007 in which former Wallabies skipper Tim Horan claims it takes 39.5 cans of Queensland beer to fill up the largest trophy in world rugby.
But, according to our calculations, the real figure should be closer to 60 cans. So either our maths is wonky, or Aussies are clueless short pourers when it comes to dishing out the amber nectar. Both are entirely likely.
The discrepancy can be at least partly explained by Horan's frank admission that his method produces a whopping half-metre head.
"You pour all the cans in and pick it up and start drinking, and the froth is well above eye-level," Horan told rugby fans at a pre-test breakfast at Eden Park in 2007 - the last time the Aussies had a shot at walking off with the cup.
That's insane. And just plain wrong. Horan's 50cm head more than doubles the height of the pour into the cup's roughly 37cm bowl. "That is too much," says Steve Plowman, the master brewer and owner of Hallertau Brewbar.
"I reckon you are looking at 15 per cent of head would be appropriate. For a vessel of that size, getting your face through the head to the beer would be almost impossible."
Former All Blacks lock Ian Jones helpfully aided the Herald's investigation by quoting the value of pi at 3.141 off the top of his head at a function in Auckland yesterday afternoon.
By our estimation, the bowl height of Lord Bledisloe's Cup is 37cm and the average radius 17cm.
There is, admittedly, a touch of rule of thumb and wild guesswork in those measurements, but by multiplying those values by each other and pi we reckon a careful effort would see the Bledisloe hold well over 50 cans of Steinlager, and quite possibly 60.
Australians have a well-established reputation as bad beer pourers, said Mr Plowman.
"Traditionally, Australians are the worst. They don't like to have any head on their beer at all."
He agreed that if they won the cup the Wallabies would almost certainly abuse it by pouring beer into it badly, although he did have some sympathy for the Wallabies' less than impressive historical efforts.
"Pouring cans into big vessels is hard and is always going to cause a lot of foam - unless you tip it right over on to its side, then you get a nice bit of gradual incline.
"But how do you drink out of something that big? That is where the real problem comes in."
In what is hopefully not a harbinger of things to come in the World Cup, Mr Plowman said the most conscientious beer pourers tended to reside in Europe: "In Europe they like a good two fingers of head."
Funnily enough, that's precisely the measurement Kiwi fans will be giving the Wallabies on Saturday night if they do break the All Blacks' 12-year grip on the cup.