For Munster, this is the point of no return. Basically, they have to tear the formbook to shreds and do what no Irish side in the European Cup has done this season (namely win away) and what no Irish side has ever done in three seasons (namely win in France).
As tall orders go then, this is alpine, although not quite as steep a prospect as it was a month ago. In that time, Bourgoin's four-year unbeaten home record was ended, first by Castres in the French championship, and then by Harlequins last week. Psychologically, this lumbering Bourgoin side will not feel nearly so invincible in their impassioned fortress of Pierre Rajon.
Nevertheless, for Munster to achieve the unlikely they will almost certainly have to do something they have not done this season to date, and that is put their necks on the line collectively and remained focussed for at least one concerted bout of pressure in their 22.
For, as sure as the locals had croissants for breakfast, Bourgoin will demand that of Munster. As much as Laurent Cabannes' sheer genius and two support tries (cue to Alan Quinlan again?), cumulative defensive resilience for much of the third quarter was the key to Harlequins' win last week.
Manager Jerry Holland accepts this has not been the most abiding strength of a sometimes porous Munster, "though the problems, as has been well highlighted, have been early on. That hasn't been a spiritual weakness, more technical, tactical or even simple concentration."
But, concerted pressure will be an inevitability, and will probably come sooner rather than later. "If you don't stand up to it and answer to it, you're going to suffer. And they (the French) do sense that weakness quicker than anyone."
Munster could be in better health, for while Killian Keane's chest injury is progressing favourably under intense physiotherapy, Conor Burke yesterday pulled out with a groin strain sustained in training on Monday. Worse still, his obvious replacement, Mick Lynch, pulled a hamstring 24 hours later.
Thus, pending Keane's continuing recovery, Munster will leave it until as late as possible before finalising their back-line, given Keane reverting to centre, with Ronan O'Gara returning at outhalf, or John Kelly moving from the wing where Andrew Thompson could be brought back, or alternatively the previously out-of-touch Sean McCahill coming in directly at centre, are all options.
Midfield will be another key area, for although Rhys Ellison is a hardy bit of stuff who has plugged some of the holes, Bourgoin have genuine, if hitherto under-used pace in midfield with the classy Stephane Glas and Yann Bohu.
First though, Marc Cecillon and the Bourgoin pack are sure to test Munster's mettle up front.
Frustrated by last week's defeat to Cardiff, Holland says Munster have "learned enough. The learning is well over. It's a case of performing."
Munster: D Crotty; J Lacey, AN Other, R Ellison, J Kelly; K Keane, B O'Meara; I Murray, M McDermott, P Clohessy, M Galwey (capt), S Leahy, E Halvey, A Foley, A Quinlan.
Bourgoin (possible): N Geany; L Leflamand, Y Bohu, S Glas, D Janin; G Cassagne, N Guilhot; O Milhoud, JF MartinCulet, P Peyron, M Cecillon (capt), J Daude, J Frier, M Malafosse, P Raschi.
Referee: C White (England)
Formguide: Bourgoin - WLLL. Munster - LLWL.
Previous meetings: Munster 17 Bourgoin 15.
Leading points scorers: Bourgoin - Nigel Geany 29. Munster - Conor Burke 34.
Leading try scorers: Bourgoin - Leflamand, Raschi, Fischer, Frier 1 each. Munster - John Lacey 4.