Rory Best believes "genetic freak" Iain Henderson has limitless Test match potential.
Lock Henderson starred in Ireland's 50-7 World Cup victory over Canada in Cardiff on Saturday, leading experienced hooker Best to hail his Ulster club-mate's rich promise.
Bullish ball-carrier Henderson now has the chance to cement a starting spot in Ireland's World Cup campaign, and at 23 remains at the lower end of a hugely exciting upward curve.
Talisman and captain Paul O'Connell will retire from the Test arena after the World Cup, and in Henderson Ireland have a ready-made long-term replacement.
"Hendy's a bit of a genetic freak, and if you give him the ball in certain situations he's very hard to stop," said Best of Henderson.
"It's great for him and to get through, a hard 80 minutes will be a big boost for him.
"He's very laid back and it's something that as he's still very young, we're trying to get him to look as though he's a bit more clued-in.
"And it's something you see every month and big game that goes by now, he just grows and gets better and better, and the big players around him and the influence of the coaches, it's all paying dividend.
"It's hard to know where the limit is with his potential.
"But he's a very chilled out guy, he spends a lot of hours in the day asleep."
O'Connell has built a formidable Test match aura across his 13-year international career, to the point where the 35-year-old has the pedigree to force contests to revolve entirely around him.
Best believes Henderson has the potential to emulate O'Connell's magnetic qualities as he hones his own approach to Test rugby.
"I think for Hendy it's about taking the bits of their game, but he has to generate his own thing too," said Best.
"Paulie has bits of his game that Hendy doesn't and he can work on that, but the flip side is that Hendy has a lot of aspects of his game in terms of athleticism and raw power that a lot of people don't have.
"So he has to mould his game, keep trying to get better, take the bits from Paulie too, because in world rugby I don't think you're going to get a better role model as a second row than Paul O'Connell.
"And he's very lucky to be playing alongside him.
"Hendy will learn from that, and get better through that.
"Hendy has to be his own player though, because he can do things on the ball that a lot of people in world rugby can't do."