At half-time the buzz in the ground was tangible. This is the Aviva for God's sake. Forty minutes later D4 was on fire as the new ground came of age.
As the Joe Schmidt era really kicks into gear, it is certainly well on the way to becoming the relative fortress it once was.
It was a step back in time as the ground heaved with atmosphere and desire.
And so too did the rugby, for this was about heart and guts and spirit. It was about resilience, about never-say-die, backs-to-the-wall defending. It was about a team prepared to go not just the extra mile but empty itself of every last ounce of energy along the way.
It brought about a win as deserved as it was hard won. Wins don't get much more satisfying than this - you reach the final whistle and you know you could have given it no more, and you realise that winning can come no sweeter.
On Saturday, for 80-plus minutes, particularly in the riveting three-penalty second half, but more than anything in the final quarter, Schmidt's Ireland gave everything.
There was no Webb Ellis trophy, no Six Nations title, no Triple Crown at stake, but this result clearly meant everything to this squad.
What an amazing game. Seventeen points to the good after even less on the clock , 20 points apiece at the break, just two penalties to one in the second half, yet it was as courageous a winning performance as ever witnessed by a team in green.
Yes it was that good. It made you mighty proud to be Irish.
True to form, Schmidt played his role down, and that of assistant Les Kiss too, but Paul O'Connell - the most appropriate man of the match ever - summed it up best when saying: "To be able to defend the way we did and not give them an easy out was very satisfying."
The master of the understatement? Perhaps, but it was typical of the humility of the man and of the values this squad and its backroom staff espouse.
By and large, I'm a fan of Michael Cheika's heart-on-sleeve type of personality.
But in terms of humility, whether in victory or defeat, he has some way to go to reach the standards set yet again by his opposite number on Saturday.
We are blessed to have Schmidt running the show and it is the players who appreciate that and acknowledge it in the best way possible.
There will be bad days and lesser performances, but rest assured they will be treated in the same down to earth way in house.
This wasn't tactical genius. Schmidt didn't outmanoeuvre Cheika, but it takes some working relationship between players and coach in any sporting endeavour to bring about what Ireland have: a group prepared to give everything they have for the cause.
The scrum creaked at times but never buckled, the lineout could have been better, but the work at the breakdown and desire in defence were phenomenal.
The Australians played it off the cuff, with wingers Adam Ashley-Cooper and Henry Speight switching flanks at random. Unstructured Wallaby rugby is a very dangerous animal, as three first-half tries amply illustrated.
Forty points evenly split, including five very different tries, made for an electrifying opening half.
And it only got better on the resumption. Even though just nine points were scored, it was thrill-a-minute stuff.
In many ways, it was the third quarter that swung it. For all their possession, the Australians could not get out of their half. There was no 'easy out'.
Relentless pressure without the ball forced the vital penalties, with Johnny Sexton (save for one first-half miss) nigh-on faultless in turning territory into points.
And while it is unfair to single out individuals, Rob Kearney and Robbie Henshaw deserve special mention - they were both awesome throughout.
There wasn't a player in green who didn't tackle himself to a standstill, and the Wallabies were every bit as committed. It made for a true test in every sense of the word.
On balance, and despite Cheika's irritating protestations, in the end the victory went where it was most deserved.
I'll leave the last word to the skipper: "We've been in this situation before and it didn't serve us well."
Grounded or what!