Jamie Heaslip holds the firm opinion that Jonath an Sexton is as good as there is in the game.
"I put him up as one of the great players of Irish rugby, and one of the great tens in world rugby.
"I put him and Beauden Barrett side by side," he said, on the Radio 5 Rugby Podcast yesterday.
More than that, the retired No 8 is adamant Sexton matches two other Irish team-mates for their innovation.
"He is doing to ten what Cian Healy and Tadhg Furlong have done to loose-head and tight-head.
"He is changing what a ten is meant to do, changing the position."
When Healy came on the scene, his dynamism in the open was new and, now, Furlong's superior skill is his point of difference.
Heaslip noted the defensive side of Sexton's game as the most under-rated element.
"Defensively, he doesn't get enough credit as an aggressive player," stated Heaslip.
"He has no problem flying up and making the tackles, taking the shots.
"He is able to do everything as opposed to tens of old that might have relied on their back rows to make the tackles."
The all-consuming nature of Sexton has led to the image of an intense player in the game and a quiet man away from it.
"I look at Johnny. I've known him for a long, long time. The guy is nuts.
"I like my tens to be a little bit crazy," stated Heaslip.
"I like my tens to be really passionate and confident because they have to be.
"They are in the equivalent of a quarterback position. They play such a pivotal role.
"Johnny is a smart guy. He loves rugby, really passionate about it, is a really good pro."
It has been said of Heaslip that he was the ultimate professional, completely dedicated to his craft.
He shared that rating with Sexton, the man who encouraged Joe Schmidt and Stuart Lancaster to come to Leinster.
"He sets the standard," agreed Heaslip. "The last couple of years, I've seen him grow, in terms of being a leader.
"Johnny has always been a very aggressive player.
"He is very attack-focused. He is always looking for the opportunity.
"He doesn't care if you are on your own five-metre line and he sees space the other side of the field.
"He will do a cross-field kick and attack from his own five-metre line. He is always attacking."
Heaslip will fly home from a short break in Portugal to attend the Champions Cup quarter-final on Sunday.
"It is going to be one hell of a game from two sides, who have really good strong attacking prowess and really good defensive systems in place that starve teams of opportunities to play."