IT was the boots that gave them away.
There was a time when you bided your time in international rugby, bedded in, but here were these new boys wearing all sorts of colourful footwear. Craig Gilroy's orange efforts were nearly as audacious as the 23-year-old loosehead prop Dave Kilcoyne wearing white. Things have changed.
The theory goes that, if you're going to wear flashy boots, then you had better be able to back it up – and Ireland's young guns did just that.
Make no mistake, Fiji were awful, but after a year of stagnation and poor results it was a breath of fresh air around Thomond Park to see Luke Marshall, Paddy Jackson, Iain Henderson, Gilroy and Kilcoyne showing no inhibitions in the green shirt.
When we will see them again is up to Declan Kidney, who admitted that taking on the Fijians is nothing compared to the intensity and power that Argentina will bring next Saturday.
But after 80 minutes of refreshing, youthful exuberance, there must be a temptation to try at least one or two of the new faces out against the grizzled might of the Pumas.
As the old timer in the side, Donncha O'Callaghan – who sported a sensible pair of black boots – couldn't deny the impressive way the newcomers took to international rugby.
Now he wants them to work on the mental side of things to make the next step up to full Test matches.
"Coming through these academies, they are alive and ready to go. Whereas a few of us weren't at that level conditioning-wise, these guys are freaks," the 33-year-old said.
"They are ready to go from a physical point of view. It is just the mental aspect of the big games, and that's what's great to see – the urgency to keep going, keep going, to put the foot down.
"I liked the ruthless streak where fellas wanted to march down the pitch and score again. I think that was a good thing and the pride in our goal-line... we'll take an awful lot from the scores we got, but keeping them to nil was important.
"I know they (Fiji) will be disappointed with their performance, but there were times when they were jamming on our line and big players like 'Hendy' (Iain Henderson) came out with big plays to keep them out."
It showed strength and know-how of someone beyond the 20-year-old's years and was further example of why Kidney and Gert Smal thought enough of the young man to cap him against South Africa.
There is more to his game, however, and the acceleration he showed in the build-up to Marshall's try was further demonstration of a special talent in the making.
"He was good," the Munster veteran said. "The big play for me was that reef near the goal-line. It stands out, a bit of goal-line pride that he wanted to have a big moment like that and turn it over.
"He's coming on, he's a great young fella, a massive natural talent. I think he'll get better at this level."
The pack provided the platform, but it was the backs who lit up the Thomond Park night.
From the moment Jackson fed Marshall who, carrying in two hands, scythed between two defenders, drew full-back Metuisela Talebula and fed Gilroy for the opening try, it was clear that the young Ulster trio were here to play.
Fly-half Jackson may have missed four of his 10 kicks at goal, but the timing of his passing impressed as he drew in Fijian defenders and waited until the last moment before releasing those outside him, often shipping big, late hits as a result.
It created space for those outside him and offered a different dimension to either of the men who sit in front of him in the No 10 pecking order.
Outside of that, Marshall was excellent, running intelligent lines, kicking well and throwing accurate, flat passes. He wasn't tested much in defence, but Kidney will be hoping that Ulster coach Mark Anscombe was taking note and will promote him ahead of Paddy Wallace at club level.
The same goes for hat-trick hero Gilroy, who has been marginalised at Ravenhill due to the return of Tommy Bowe.
The winger gave a display of pace and confidence that was a joy to behold.
"A couple of them – Iain Henderson and Paddy Jackson – are only 20," Fergus McFadden said with admiration. "Paddy, in particular, deserves special praise. To come in at out-half, playing international rugby at that age, is a testament to him.
"He's a great player and he's a nice guy who has been a breath of fresh air since coming into the squad. I don't think I'm over the hill myself at 26, but these guys are a lot younger and it's nice to see them come in and doing well.
"Lads like Craig Gilroy and Luke Marshall haven't played a whole lot of rugby for Ulster and I thought they both had good games."
The kids may be alright, but it remains to be see if the coach will trust them. On this evidence, he should.