Suddenly he's the focus of attention; playing for Munster against the Rest of Ireland in front of 10,000 one week, obtaining writer's cramp after training sessions the next and contemplating a European Cup semi-final against Stade Francais' all-international backrow.

Donnacha O'Callaghan is doing his damnedest to keep this all in perspective.

"I'm kind of being a bit sceptical about the whole thing. I don't want to let my head get up in the air. I suppose if you go back a few weeks most people wouldn't have heard of me. So this is a good high and I'll just take it for what it is."

Whether completely indicative or not of him, that's a pretty level-headed approach for a 22-year-old.

He's been well groomed for this, mind, and is on the first wave of Ireland's new breed of professional young rugby player.

Aside from being well tutored by his older brother Ultan (by eight years to the day), Donnacha has been through a somewhat classical route - Munster Schools Cup-winning CBC Cork side, Irish Schools, Irish under-19s and IRFU Academy to first fully fledged professional season with Munster.

"All my brothers (he's the youngest of four) have been a big help in different ways, but obviously in rugby Ultan has been a big help.

"Just the little stuff. In the last year or so there would have been games when fellas were on my back and stuff, who try to rise you. Before I'd go after them and give away stupid penalties but Ultan's been keeping an eye on me to give me the nod and leave it off. He's helped me be a bit smarter."

This tallies with a less abrasive impression of the younger O'Callaghan this season, one more inclined to look for the ball than the man.

"To be honest, I would always have seen my penalty count to be unnecessarily high. Like, hitting a fella a dunt, just silly."

Playing regularly with a tabletopping Constitution side has done his confidence no harm either, even if it has been largely in the second-row. "I was always on edge with Con, but now it's settled down a bit and Mick (O'Driscoll) and myself are making a go of it, and Ken Murphy has been a great help."

He considers second row his main position, though that said the greater exposure of blindside flanker has given more opportunity for him to display his superb physique and athleticism.

"Maybe because I'm a bit fitter this season you can take up good lines of running at number six. The games I've played there I've been quite happy with."

Now comes the biggest game of his fledgling career, against monsieurs Moni, Juillet and Pool-Jones or Tabacco.

"We were looking at the video today and you'd have a look at the players you'll be playing against.

"You'd respect them of course, but I wouldn't fear them to be honest. These are the players you want to be playing against at this level. So hopefully it will all go well."

Nor could he be stepping into a better set-up or, one imagines, a better group of players. "The main thing is once you've the respect of the lads around you, that picks up your confidence an awful lot.

"Now it's down to a `t', we're running off plays and there's no real questions, and that's what you play rugby for. The respect of the players around you."

"He's got everything football-wise and he's as geared for this Saturday as anybody could be in his position," says Niall O'Donovan.

It's a big ask then, one you would have feared for of a comparative European debutant a few years ago, but this 22-yearold could have the answers.