The near neighbours faced off for just the second time in 20-over cricket at the MCG, with England taking up a familiar position as heavy favourites in the Super 12 clash.
But they found themselves on the receiving end of a remarkable bloody nose, sliding to a five-run defeat after failing to keep up with the Duckworth-Lewis-Stern rate when rain forced the teams from the field.
It was a famous result and one that was richly earned. An 82-run stand between Balbirnie (62) and Lorcan Tucker (34) laid the foundations with bat, before Josh Little took two quick wickets with the new ball to lead a steadfast defence.
The celebratory scenes at the close, as the boys in green embraced their friends, family and followers in the stands, were reminiscent of a famous triumph at the 50-over World Cup in Bengaluru back in 2011.
Back then it was all-rounder Kevin O'Brien whose record-breaking century downed England and put Irish cricket on the map, a feat that now has a fitting contemporary companion.
"It's surreal, an absolutely surreal feeling. It happened too quickly to take in what we have just achieved," said Balbirnie, who was named player of the match.
"In T20 cricket it's probably the best (win ever). I've played in this team for a number of years and we've never had a result like this.
"We came into this round knowing any win we got would be a huge achievement and we've beat the best T20 team there is in my opinion.
"I looked through their team this morning, looking at match-ups and part of me was struggling to understand how we could compete with them if they showed up."
On the transitional shift from the previous generation of giant-killers, who also shocked Pakistan in the 2007 World Cup on St Patrick's Day, Balbirnie added: "We knew we needed to kind of move from players like that.
"Kevin recently retired, he's one of the best cricketers we've ever produced and I probably didn't get the chance to say that at the time.
"It wasn't easy to leave him out of squads, but guys have come in and shown it's not just that generation that is a golden generation.
"With Harry Tector, Lorcan Tucker, Josh Little, Mark Adair…this is a special group of cricketers. That generation laid the platform for us to be professional cricketers, we wouldn't be here without them, but we have a duty to take the game forward as much as we can.
"We did the museum tour here (at the MCG) last night. Ronnie Delaney won a gold medal here in the Melbourne Olympics and you see his name etched in the history of Irish sport.
"I hope we've done something similar. I've always said cricket isn't a big game in Ireland but we're the flag bearers and we want it to be as big as possible."
The result means qualification for the semi-finals is now impossible to predict, but Balbirnie is delighted simply to be in the mix having fought through the first round to get this far.
"It's a huge game for us against Afghanistan on Friday," he said.
"The attitude we've had for the last few days is 'who knows what can happen?'.
"The group is wide open and we're part of that. If we come up short, so be it, but we'll definitely give it a crack."