Best result from Munster's point of view is that Northampton gain revenge for that defeat by Scarlets in Franklin's Gardens. In that case, a win sees Munster qualified.
If Scarlets win without a bonus - and Munster do likewise - the quarters beckon for Tony McGahan's squad with a game to spare.
And if at the outset of this year's competition, you'd gone into a Bookies and asked for the odds on that, those odds proffered would have been in double digits.
Extraordinarily, Northampton, in third place on 8 points, after three losses, could mathematically still win this group were Munster to slip up tomorrow and that's a scenario McGahan seemed acutely aware of at Wednesday's Media gathering.
"Our focus is firmly on our own performance, on what we need to do to get the win, just that, nothing else. Our thoughts are fixed on Saturday, nothing beyond that." he said refusing to enter into any discussion of bonus points or quarter final permutations.
Nor was his young scrum-half Conor Murray interested in any such imaginings, "Anything beyond the game on Saturday hasn't been discussed at any session. This is all about Castres and what we need to do to get a result. They held Northampton scoreless for long part of their away game and that in itself should serve as a warning. I don't see them coming over here just for the trip.
"But" he continues, "the training was good this week, every bit as intense as any other session and I think that augers well for what we're facing into."