Opportunity knocks for Munster at Thomond Park this evening.
Depending on results elsewhere, and presuming they can maintain their unbeaten record, Tony McGahan's men can secure a Heineken Cup quarter-final berth.
Bizarrely, Northampton can still emerge as group winners should Munster implode during this next fortnight; hence any hint of complacency will have been decisively sundered within the confines of the Munster dressing-room.
The near-fatal effort against Montauban's second-string two seasons ago at this ground inures the Reds against any vaulting ambition, even though many thoughts will be cast forward to next week's trip to Milton Keynes and a potential quest for a home quarter-final.
Given the squad's travails last season and the injury ravages that have beset them this season, qualification by itself will be a noteworthy achievement; pursuing further aims will only be achieved by firstly taking care of business today.
Munster remain unchanged but Castres have expelled all but four of the first-choice Top 14 title-chasing combination that defeated Perpignan so impressively over the festive period.
Pierre Bernard starts at fly-half while young Romain Martial is at full-back. Of more interest are those who remain behind, amongst them Max Evans, Marc Andreu, Chris Masoe, Joe Tekori, Luc Ducalcon and Romain Teulet.
Scott Murray, Seremaia Bai, Rory Kockott and Mathieu Bonello do travel, but are benched.
"I don't know if we have the ability to look that far ahead," appreciates McGahan.
"The way the campaign has been so far -- I don't have the ability to look too far ahead. That's just where we are.
"Maybe other sides have that ability but we certainly don't. All we need to do is focus on ourselves and be ready for 3.40 on Saturday. We also recognise that if we get our job done there is a quarter-final place there.
"Hopefully then we can have no more injuries and have a squad to go through to Northampton. How do we prepare for that? We'll deal with that when we come to it."
Munster -- D Hurley; J Murphy, K Earls, L Mafi, S Zebo; R O'Gara, C Murray; W du Preez, D Varley, B Botha, D Ryan, P O'Connell (capt), P O'Mahony, N Ronan, J Coughlan. Reps: D Fogarty, M Horan, S Archer, D O'Callaghan, B Holland, T O'Leary, I Keatley, D Barnes.
Castres Olympique -- R Martial; V Inigo, P Bonnefond, P Garcia, P Lakafia; P Bernard, T Lacrampe; S Taumoepeau, M Rallier, A Peikrishvili, M Rolland (capt), R Capo Ortega, Y Caballero, S Malonga, J Bornman. Reps: M Bonello, M Coetzee, K Wihongi, S Murray, I Diarra, R Kockott, S Bai, M Nicolas.
Ref --A Small (England).
Munster v Castres,
Live, Sky Sports 1, 3.40