The first time Conor O'Shea trained with Brian O'Driscoll his jaw dropped.
The first time O'Shea played with O'Driscoll, his jaw broke.
On both occasions Harlequins' director of rugby remembers being spellbound by a centre he believes will go down as "the greatest player of his generation".
"It was 1998 going into 1999 and Warren Gatland brought two young players down to a training session in Galway: Brian O'Driscoll and Gordon D'Arcy," O'Shea told Press Association Sport.
"Warren took four or five of the senior players aside, and said 'will you look after these kids, I wouldn't mind you telling me what you think of them'.
"After the session he came up to us and said 'what did you think?'
"And we said, 'can you play them now please? Because they're miles better than we are'.
"They were just incredible, the two of them.
"Gordon took a little bit more time to get there. But D'Arcy and O'Driscoll, as a centre pairing for Leinster and Ireland, you talk Horan-Little, you talk about those great centre pairings - Guscott and Carling - D'Arcy and O'Driscoll will definitely go down in that company."
O'Driscoll will extend his world-record Test appearance tally to 141 in his final Ireland bow against France in Paris on Saturday, before retiring in the summer.
The 35-year-old made his international debut in Ireland's 46-10 defeat to Australia in Brisbane on June 12, 1999.
O'Shea lined up at full-back that day, breaking his jaw and winding up eating through a straw thanks to surgical re-wiring.
The former London Irish full-back might have been dazed and confused by his injury, but admitted he was dumbfounded by the natural talent in front of him as O'Driscoll embarked on his path to greatness.
"All I remember is the lads bringing burgers and leaving them outside my room after the game, knocking on the door because they knew I could only have liquidised food," joked O'Shea.
"Straight away you knew with Brian, that he was something special.
"And all these years on, he has become the greatest player of his generation: unequivocally.
"He's just incredible. That bloke is still at the very top of his game.
"He's had 15 years of shoulder surgeries, being targeted, being the man everyone wants to have a go at. He's won the Grand Slam, Heineken Cups, RaboDirect Pro 12 titles, the Amlin Challenge Cup.
"You can never compare eras, I think that's unfair, but of his era, I can't think of a better rugby player, and also a nicer bloke.
"If you want to go out have a few beers and meet someone who hasn't got above themselves, then I don't think you can go too far wrong with Brian."
O'Driscoll and D'Arcy will extend their world-record international centre partnership to 56 appearances as Ireland chase the Six Nations title in France.
Leinster stalwart O'Driscoll's hat-trick shocked the continent when Ireland edged out France 27-25 in Paris in March 2000.
O'Shea backed the departing modern great to produce a performance to rival that landmark showing at the Stade de France on Saturday night.
"O'Driscoll and D'Arcy are a pair you would go to war with," said O'Shea.
"I loved that New Zealand game in November, their performance just rolled back the years, it was just these two warriors standing up.
"It's almost fitting Brian's last game will be in Paris.
"I wouldn't put it past him to do something special there, because it's where he really signalled his arrival on the world stage with that hat-trick.
"And who's to say he won't finish off with something special out there again."
O'Driscoll surpassed George Gregan's 139-cap Test appearance record in the seven-try Italy blitz.
Former Wallabies scrum-half Gregan admitted he was pleased it would be a stalwart like O'Driscoll to pass his record milestone.
Gregan played for Australia in O'Driscoll's Ireland debut in 1999, aware straight away the wily centre was a star in the making.
Zambia-born Gregan believes All Blacks flanker Richie McCaw will eventually overtake O'Driscoll's caps record, the 33-year-old already boasting 124 international appearances.
"You could tell early on he was a player of high quality, and a genuine game-breaker," said Gregan.
"That has continued throughout his entire career.
"It was always going to be broken by someone like Brian, and even Richie McCaw, he looks like he will pass it too.
"They are both wonderful players of world rugby, who've always displayed consistency, resilience and a high level of performance.
"So I couldn't be happier it is Brian to move past the record.
"Brian has always had that burning desire, and so it is only fitting he will end up with his name in the history books."
Live television coverage of the RBS 6 Nations from 12:00 on Saturday 5 March (12:30 Italy v England, 14:45 Wales v Scotland, 17:00 France v Ireland) on RTÉ Two and RTE.ie (Ireland only). Live radio coverage of France v Ireland on Saturday Sport (14:00) on RTÉ Radio 1 and RTÉ.ie (Worldwide).