"It is obviously quite a complex calculation. We have looked at it. The bottom line is that we just need to beat Argentina," confirmed Ireland team manager Mick Kearney.
The Pumas, in sixth, are one place ahead of Ireland on the current list and will bring their customary 'brio' to bear of what is fast turning into a very important international.
An Ireland defeat to Argentina would be their third reverse in four 'big game' matches between the countries since Lens in 1999.
There followed a sequence of matches between the two countries that were often marred by ill-feeling, off-the-ball incidents and genuine bad blood that was often spilled.
This would spell disaster and throw up a World Cup Pool that could include any one from New Zealand, South Africa or Australia as first seeds and, possibly, England, Argentina or Wales as a second seed.
"We are basically just concentrating on the performance against Argentina. Rankings are obviously hugely important in terms of the World Cup," said Kearney.
"At the end of the day, what is in our control is going out and putting on a performance against Argentina. That will be the sole concentration."
The talk of transition is well-merited. Kearney was ready with a single knockout statistic that put into perspective the different animal Ireland is this week than at the World Cup.
"If you look at the squad back then and the squad today, there are 17 changes. That is a pretty massive turnover in anybody's language. There have been injuries in the squad, retirements in the squad and selection decisions made as well," he said.
Flanker Peter O'Mahony identified the breakdown as the key area on Saturday and also "as much a backs issue as it is for forwards".
Of course, it almost has to be for Ireland given how they have not opted for an out-and-out openside since the days of Keith Gleeson and his selection was not exactly set in stone.
There is a stonewall texture to Argentina's attitude to defence and they have a world-class back row headed by a superb captain Juan Fernandez-Lobbe.
"We are going to look for a physical performance from one-to-fifteen. As a fifteen, they are accurate.
"That is what you want at the breakdown," said O'Mahony.
"There are fellas that have won a Grand Slam. We are trying to create our own piece of history at the moment."
It would be a good start to qualify Ireland as a second seed for the next World Cup.