Leinster v Harlequins, The Aviva Stadium, Today (KO7.45) - BTSport.
The competitive advantage Leinster hold over Harlequins is staring them straight in the face.
There was a lack of authority to Tim Swiel's play last week that gave an outward impression of inner fragility.
There was a rabbit-in-the-highlights gaze from the 21 year-old when he was summoned to the centre of a European battle and expected to lead where Nick Evans had led.
The former Natal Shark was signed by Harlequins as recently as October to replace the injured Ben Botica.
Swiel had played just three times for a total of 121 minutes when he was pressed into service for Evans last Saturday.
He is not the only one on a voyage of discovery. But, former England U20 captain Jack Clifford is a natural leader.
The 21 year-old has been in the 'Quins system for some time and has represented the club for 14 caps already, seven times this season.
"Yeah, that's the reality. You're going to get after those guys and expose any weaknesses across their side by our intensity and our accuracy," said Leinster coach Matt O'Connor.
"If we can deliver on those bits across the course of the game, well then, we'll be asking questions of the whole group."
The absence of Chris Robshaw will deny Harlequins defensive nous.
But, Luke Wallace will be freed up in his role as a natural, groundhog openside.
This is where the recall of Dominic Ryan can work to counter him.
The life and time on the ball for Swiel and Clifford will be made a whole lot easier if Joe Marler, Dave Ward and Will Collier can dominate the scrum engagement.
This will be one hell of a dust-up with Jack McGrath, Sean Cronin and Mike Ross frothing at the mouth to get their retaliation in first at the scrum.
"It's going to be like all big games: the platform will be set up front," said O'Connor.
"The first two or three engagements in that area are going to be important in creating quality pictures and momentum and confidence for either team."
The fact that Leinster gave Tadhg Furlong four minutes from the bench last week and no time at all to Bryan Byrne or Michael Bent doesn't communicate confidence in what is effectively their third choice front row.
"They didn't play much last week but they have played a lot of rugby," stated O'Connor.
"So, if required, I'm very confident that they will come on and do a job for us."
Leinster: R Kearney; Z Kirchner, L Fitzgerald, I Madigan, D Fanning; J Gopperth, I Boss; J McGrath, S Cronin, M Ross, D Toner, K Douglas, R Ruddock, D Ryan, J Heaslip (capt).
Harlequins: M Brown; M Yarde, M Hopper, G Lowe, A Tikoirotuma; T Swiel, D Care; J Marler (capt), D Ward, W Collier, C Matthews, G Robson, L Wallace, J Clifford, N Easter.