Nacewa must look to plant doubts in the mind of Wasps All Black Piutau
Former Auckland Blues mental skills coach Isa Nacewa will look to take a walk inside the mind of Charles Piutau tomorrow.
Surely the last thing All Black Piutau would expect to see on his Champions Cup debut for Wasps is his coach of no more than five months ago standing directly in front of him.
It is one thing to know a player inside-out, another to know the man from the inside-out.
Cue Leinster captain Nacewa. The 33-year-old spent the best part of two seasons employed in assisting Auckland prepare for matches.
Coach John Kirwan and Nacewa worked on a psychological edge they called 'Bone Deep Preparation' for Super Rugby.
While the overall benefit to those Blues was questionable given their successive-season finishes of fifth-last and second-last, there were individual success stories.
"Look, Charles Piutau was just absolute world-class - very humble," reflected Nacewa. "He is very hard-working and reads the game really well.
"He'd do a lot of work in analysis and in front of the computer too. He proved himself at All-Black level before the World Cup squad got cut.
"He's above his years too," he added, in reference to Piutau's relatively young age (24).
Wasps carried out a smart piece of business to take him for one year only before Piutau decamps to Ulster.
"He's been part of that All Black environment. He has a level of excellence that he holds himself to. It's pretty bizarre that you would have classed him as one of the senior players, especially in the back-line, for the Blues."
Nacewa will have a better understanding of Piutau's strengths and weaknesses than the man himself.
It remains to be seen how Leinster can expose any frailties - there are very few - and can control the clear dangers from such a multi-skilled counter-attacker.
Maybe, just maybe, the difference between Leinster and Wasps can come from the fact that the Irish province's brightest star will have more touches on the ball.
Jonathan Sexton has been brought back for moments like these.
The sad retirement of Kevin McLaughlin left Leinster with a leadership deficit.
Nacewa has stepped into the breach even though there are disadvantages to the captain often being the furthest man from the action.
This is where the experience of Jamie Heaslip will come into the equation as a second voice.
This leaves Sexton free to lead through word and deed, decisions and executions.
"Johnny's in a class of his own," said Nacewa. "I don't need to talk to him about managing a game."
The responsibility for Nacewa is to lead from the back, so to speak, set up a closed shop and provide that level of security necessary for those occupied ahead of him.
"It is just about me going out there and doing my own job to the best of my ability."
That is all he has ever done in blue.