It is the selection of Ireland loose-head Cian Healy over South African tight-head CJ van der Linde that will raise the most eyebrows in an incredulous Toulouse camp.
The explosive Healy, 22, has been largely relegated to the go-slow inconvenience of bench time since his draining experience in the Six Nations.
Once again, the versatility of Cook Islander Stan Wright in moving across to be the cornerstone of the scrum illustrates the indispensable contribution made by a player initially thought to be a journeyman short-term filler of a signing in the autumn of 2007.
Coach Michael Cheika relayed how Toulouse tend to bring in an entire new frontrow around the 50-minute mark. Perhaps he will summon Bernard Jackman, Van der Linde and Mike Ross forth from the bench to counteract this tactical move.
The pressure will weigh on the relatively slim shoulders of Shaun Berne now that Jonathan Sexton (broken jaw) and reserve kicker Fergus McFadden (calf) have been judged hors de combat.
Really, it was a long shot that Sexton would come through. Presumably, Cheika has been preparing with Berne at fly-half, relying on his experience and distribution skills.
The kicking statistics suggest Leinster will have to execute a similar game plan to that which slashed and burned Toulouse in 2006 because Berne is not likely to return the percentages required from boot on ball.
They will have to come up with tries against what is an all-French backline. Maybe, just maybe, Berne can be their secret weapon, their dark horse for the correct course of action.
Toulouse's wily coach Guy Novès has made a few hard decisions, preferring the pragmatism of David Skrela over the flair of Jean Baptiste Elissalde at out-half and the nous of Shaun Sowerby over the power of Louis Picamoles at No8.
It is difficult not to conclude that Sowerby will be given a minder's role to shadow the movement and game-breaking threat from Leinster's best player, Jamie Heaslip.
Munster coach Tony McGahan is relieved to welcome back wing pair Doug Howlett and Ian Dowling to what is an unchanged side from that which nailed Northampton Saints in the quarter-final for tomorrow's visit to San Sebastian for the semi-final against Biarritz.
"Obviously we're happy that both have managed to get themselves ready in time. It's a tribute to their hard work and professionalism, and also to the Munster medics and fitness staff, that they are in the side.
"Players of their experience are crucial in games like this, and this is a game that is going to require that and a lot more to win," said McGahan.
McGahan will be chuffed to see Iain Blashaw and Ayoola Erinle along what is a very uninspiring Biarritz three-quarter line now that Damine Traille has been removed from the equation.
Unsurprisingly, France No8 Imanol Harinordoquy has overcome the setback of a broken nose last week to take his place in the middle of the backrow.
> Toulouse v Leinster, today, Sky Sports 3, ko 3.45
> Biarritz v Munster, tomorrow, Sky Sports 2, ko 3.15