It would have been disconcerting for an experienced senior player so it's reasonable to suggest that for a 19-year-old making his first competitive start in a Leinster jersey it was nerve-shredding.

A kick charged down after just 18 seconds of the match and Ospreys centre Andrew Bishop wheeling away in delight having touched down under the posts is not the perfect debut.

If Carlsberg did nightmares, this would have been a doozey. Robert Kearney was determined not to buckle and would go on to offer substance to that aspiration. Sitting in the David Lloyd fitness centre he sifts through the episode:

"After the kick I was determined to bounce back. We walked back and Girvan (Dempsey) said to forget about it. It's a good sign of character if you can get (your head) back and that's what I wanted to do.

"I didn't fully do it. I still made errors. After the game I was in dreadful form. If the pace of the game and the physicality - I got a few big hits - were too much for me then I would have had to hold my hand up and say I just can't handle this. Because they were such rudimentary skills that let me down, well that's what annoyed me most. It did put a black mark on the performance.

"(It was) the worst possible start, the script could not have been any worse. The kick ultimately was my fault, my responsibility. The Ospreys play a rush defence and the ideal thing was to take a three-man smacking and retain the ball. It was a bad mistake."

Kearney is being a tad over-critical. Flawed decision-making and execution before the ball reached his hands contributed to the try. He went on to recover enough to offer cameos of his ability: one glorious break from his own 22 and the calm way he took his try after Dempsey had unlocked the Ospreys defence.

There were one or two glitches, a couple of knocks-on that stung the young man's pride. Selected on the opposite wing for last weekend's match against Glasgow, Kearney grabbed another try, this one a little more straightforward. And so in three games in the Leinster jersey he has notched five tries, including a hat-trick against Overmach Parma in a pre-season friendly.

His speedy progression to the senior ranks is underpinned by outstanding underage promise from the moment he announced his talent at Clongowes Wood College, helping them to a Leinster Senior Cup final appearance before losing to Blackrock College.

He played Leinster and Ireland Schools and captained Ireland at the Under-19 World Cup in South Africa. He also played underage soccer with Dundalk and spent two years on the Louth minor football team, the first as a 15-year-old.

"My parents were always keen that I did a bit of everything. Gaelic, golf, soccer and rugby were the main ones. As a kid, Gaelic (football) was number one. I played for Louth minors for two years. I live beside a vibrant club in Cooley Kickhams.

"Before I went to school, Gaelic football was the one I played most. Soccer and golf (Greenore Golf Club) were more a leisure thing, just a bit of crack with the lads.

"I played mini-rugby in Dundalk from the age of eight or nine. My dad had played a lot for the club and is still a keen supporter. I loved sport so my parents were forced to drive me all over the place to keep me happy. When I went to school (Clongowes), the two sports were Gaelic and rugby.

"There was never really a conflict because Gaelic was more of a summer sport while rugby was confined to the winter. It was fairly easy to play both of them. Rugby (though) was always number one from those days and obviously still is but I do miss not being able to play a bit of Gaelic."

Compensation comes in his rapid elevation to the senior ranks.

"Three months ago I would never have foreseen where I am now. In the middle of August I was taken up (to the Leinster senior squad) just on a trial period. Things went pretty well and one thing led to another."

His parents and friends, who offer him no latitude if he threatens to lose the run of himself, have inculcated Kearney's modesty. He also possesses a maturity that should help him deal with the pressures: this young man is a seriously gifted rugby player and it's not an accident he's gate-crashed the senior ranks already.

"I love a good challenge. If I come up short then it's a good learning curve. I then know what I have to work on and how much I have to improve. In terms of professional rugby I just love the game - it's just something I wanted to do."

The way he bounced back from that Ospreys disaster suggests Kearney has the character to match his obvious talent: a potent cocktail for Leinster supporters to enjoy in the short and long terms.