With Seán O'Brien's hamstring giving way, it means Leinster have to travel to the sold-out Matmut Stadium de Gerland in Lyon without the fantastic four of Jamie Heaslip, Cian Healy, Rob Kearney and the British & Irish Lion from Tullow.
Were all of them fit and firing, the odds would still be heavily stacked against a repeat of what happened in the 2012 European semi-final against Clermont-Auvergne in Bordeaux.
Those boys in blue Kearney and Healy combined for what turned out to be the match winning try early into the second-half.
It was the sunny setting for one of Kearney's best performances for Leinster and for Jonathan Sexton's ice-cool kicking to keep them one step ahead.
Stade Chaban Delmas was also the ground at which Gordon D'Arcy made the miracle hit on Wesley Fofana to deny a 79th minute try.
But, it was O'Brien who ended the epic duel with a killer poach on Vincent Debaty in the shadow of his posts.
Shortly after, Leinster wiped the Twickenham floor with Ulster for their third Heineken Cup in four years.
The legacy was a dynasty illustrated in the three stars still emblazoned on the their shirts.
From that day, five years ago, Leinster retain just three men in Sexton, hooker Richardt Strauss and captain Isa Nacewa tomorrow.
This looks like a fair exchange as Clermont call on just four in centre Aurelien Rougerie, scrum-half Morgan Parra, hooker Benjamin Kayser and tight-head Davit Zirakashvili.
This is where the deep pockets of the French club come into play.
For instance, in the backline, they have been able to sign current first choice France internationals in full-back Scott Spedding, centre Remi Lamerat and out-half Camille Lopez as well as England internationals David Strettle and Nick Abendanon.
Leinster have been restricted to the signing of Robbie Henshaw as their Academy production line has rolled off Joey Carbery, Garry Ringrose and Luke McGrath.
For all that, Leinster (37) and Clermont (34.3) have registered more points than any other clubs in The Champions Cup this season.
It has all the makings of fireworks in front of 40,000 spectators.
Invariably, these semi-finals are not high-scoring matches and defence often overrides attack as the pressure grows not to be the one who makes a mistake.
This is where the influence of Stuart Lancaster counts most.
The challenge is to keep playing the way they have been to break try-scoring records in the PRO12 League.
"I think you've got to, really," he said this week.
"You've got to be aware when you're playing any team in France not to give them a start.
"That allows them to build momentum and belief in their game.
"There's absolutely no doubt in my mind that if we have a positive mindset to play the game from the first to the 80th minute that we can cause some problems.
"We saw both in the qualifying rounds but also in the PRO12 as well.
"We wouldn't have scored 86 tries by accident."
The Blues front row is the only one in Europe with a 100% return from its' own scrum ball with British & Irish Lions Jack McGrath and Tadhg Furlong packing down either side of Strauss.
The physical state of Kayser and Zirakashvili - they were both injury doubts - has to be tested.
No doubt, Clermont will be eager to exploit their perceived advantage in the back row.
They will see Rhys Ruddock, Dan Leavy and Jack Conan and interpret them as something less than they were expecting, now that Sean O'Brien and Jamie Heaslip are out of the picture.
This would be a big mistake.
The time has come for Leavy and Conan to show Europe what they believe to be the truth.
They are there to take over the shirts as the coming men of Irish rugby and they also have the reassurance of back-up from Josh van der Flier, last week's Man of the Match in Connacht.
It could just be the case that this test comes one season too soon for too many of Leinster's young men.
Leinster: J Carbery; F McFadden, G Ringrose, R Henshaw, I Nacewa (capt); J Sexton, L McGrath; J McGrath, R Strauss, T Furlong, D toner, H Triggs, R Ruddock, D Leavy, J Conan.
Replacements: S Cronin, P Dooley, M Bent, R Molony, J van der Flier; J Gibson-Park, R Byrne, Z Kirchner.