Northampton Saints could well replace the exceptional ill-discipline of Dylan Hartley for that of Calum Clark's at the Aviva Stadium.
Leinster hooker Sean Cronin can't afford to take a look over his shoulder for a swinging forearm or a flying elbow, like the one with which Clark grazed Donncha O'Callaghan a few weeks back, when there is a job to do.
"I always thought he was pretty calm and level-headed," said Cronin, about his previous experiences with Hartley.
He was at a loss to understand the act of violence to the side of Seán O'Brien's head.
"When he came on that time we managed to get two scrum penalties and I don't know whether that fired him up.
"It was obviously rash what he did, stupid, and he'll have to deal with it this week, whatever happens.
"I'd day there's no-one kicking themselves more than himself this week."
The removal of Hartley for what is presumed to be a long-term ban (he will learn his fate tomorrow) could well lead to an improvement in the Saints as all is not right at the East-Midlands club.
Director of Rugby Jim Mallinder saw fit to keep the England captain on the bench for their most pivotal European night, to this point.
Then, there was the bizarre decision to withdraw captain Tom Wood, who was having a blinder.
"I don't really know, you hear a few noises around the place," considered Cronin.
"There could be something up with the club situation. I hadn't heard it before."
The return of Clark would place another ticking time bomb at the heart of the action.
While Clark is notoriously indisciplined, there are rugby reasons why he has survived.
"Perfect example, he didn't play three years ago when we played them over there," said Cronin.
"Then, the following week, he came over here and did an absolute job on us in terms of our breakdown.
"We couldn't get anything going.
"Again, his disciplinary record isn't great, but when he's on his game on his day, and focused, he's a very good player and caused us a lot of problems the last time.
"We'll have to be ready for whoever they have in their back-row this weekend."
Ironically, rugby is a sport where you can express your aggression legally.
There is no need to swing outside the rules of the game.
"It's very hard in today's game to get away with stuff. There's camera angles everywhere," noted Cronin.
"You're hoping that's the protection that you need from them, from the referees and the ARs (assistant referees) and the TMOs (television match officials).
"That's the trust we have to have in them.
"Then, we focus on playing the game, playing it clean and playing it hard.
"That's what we do at Leinster."