This is the sixth edition of the IRB Junior World Championship and this result will rank right up there with Ireland's best since the inaugural Under-20 tournament in 2008 and further back into the U-21 grade.
Wins were hard to come by for Irish sides in the early years of the Championship - they finished ninth overall in both 2008 and 2010 and eighth in 2009 and 2011 - before Niall Scannell led the 2012 team to a superb fifth place finish in South Africa last summer.
Mike Ruddock's current crop, who include Scannell's brother Rory, have designs on at least matching that achievement and Wednesday's downing of the Junior Wallabies certainly gives them a great launching pad in France.
The gritty 19-15 success, copperfastened by Tom Daly's fourth penalty of the night late on, brought back memories of Ireland's shock day one victory over tournament hosts South Africa last June.
Current captain Luke McGrath, the only returning player to feature against the Baby 'Boks, was beaming with pride when reflecting on how the Pool B opener went for his charges.
"I'm very, very proud. It was a very tough game, we are absolutely over the moon with the win but it was a bit scrappy out there," said the Leinster scrum half.
"I think the (hot) conditions played a big part in the game, something we are not used to back in Ireland. The boys stuck in, dug deep and I am delighted with the win.
"We are a very optimistic team, I feel like we need to improve a bit of everything but maybe there are silly kind of 50-50 passes we threw that gave Australia the ball a bit easy and maybe the rucks as well, but I'm sure we will enjoy tonight and get back on the paddock."
McGrath was in talismanic form, playing a great link role between the forwards and backs and keeping Ireland on the front foot in a tight second half - two particular highlights being an arcing run up to halfway and a well-judged touch-finding kick on the right.
Ireland beat England and France in Athlone during the Six Nations, but suffered narrow defeats away to Wales and Scotland and ended the Championship by drawing away to Italy.
They seem to have come back a stronger outfit from those frustrating spring reversals, showing impressive composure to close out the result against an Australian side that was captained by Curtis Browning, a back rower who made his Super Rugby debut for the Queensland Reds in March.
The 106kg Browning was an example of the bulk at Australia's disposal and how Ireland negated the Junior Wallabies' weight advantage was a key factor, something which head coach Ruddock picked up on in the aftermath.
"It was a really physical contest, Australia were much bigger than us, particularly in forwards so we really had to work up front," said Ruddock, now in his third season with the Ireland Under-20s.
"Our scrum technique I thought was excellent as against such big opponents we had to be low and we had to be technically very, very good as an eight and I thought for the majority of game it held up against big men."
The starting front row of Peter Dooley, George McGuigan and Adam Boland did really well in that regard, particularly tighthead prop Boland who, in his first start for the U-20s, was giving away 23 kilos to scrum opponent Silatolu Latu.
On the other side, Dooley also had a bigger rival to contend with - Oli Hoskins is 16 kilos heavier than him - but the Lansdowne duo, combining with Exiles hooker McGuigan, produced the goods at a succession of scrums.
Boland's low body angle and scrummaging technique meant he was more than a match for the powerful Latu. Twin brothers, Bryan and Ed Byrne, and Ryan Furniss, who were all introduced as second half replacements, also showed well in the set piece.
As Ruddock's squad recover and move on to Sunday's clash with Fiji, he added: "It was very hot (out there), the boys lost a bit of weight in that heat. We'll regroup and we'll have a look at Fiji now. We won't spend too much time celebrating."