The lines between glorious success and heroic failure were defined at Stade Pierre-Mauroy as Robbie Brady's late header sealed the Republic of Ireland historic passage to the last 16 of the European Championships.
Brady leapt, just as Ireland had squandered another chance and the game seemed to be ebbing to a disappointing draw, to head past Salvatore Sirigu and booked a date with the hosts France in Lyon.
It was a performance of rare control and purpose from Martin O'Neill's side, the best of his tenure, and called to mind the side's last big performance on French soil, the World Cup play-off second leg in Paris in 2009.
This Irish team is not synonymous with adventure and attacking intent, but they showed enough confidence on the ball to trouble the Italians and, though they didn't create a huge number of chances, they made enough to force Italy to rein in their own attacking instincts.
And, in the end, they only needed one chance of their own as, while Italy did hit the post late on, they rarely suggested they were likely to do any more than eke out a draw in a game that was meaningless for them with top spot already secured.
The atmosphere around the stadium before kick off was unusually relaxed, with many (mainly Irish) patrons enjoying the environment of the university adjacent to the stadium rather than piling into the bars.
Inside, the closed roof lent the feel of a nighttime game despite the stone-splitting heat outside, the early forecast of rain (for which the roof had been closed to protect the pitch) having proven inaccurate.
Meanwhile, the acoustics of the enclosed stadium meant the anthems were sung at a deafening volume and the response to each contentious decision amplified dozenfold.
In spite of the changes on both sides, the game began at a ferocious tempo, with Stephen Ward upset early on by a thunderous (but more or less fair) challenge from striker Simone Zaza, while Jeff Hendrick was lucky not to be booked for a strong tackle from behind.
Stephen Ward and Federico Bernardeschi – who eight months ago was sent off for Italy's under-21s against Ireland – went toe to toe, literally, the clash of boots leaving the two men momentarily writhing in pain.
Already it was clear the pitch was cutting up, the plethora of sliding tackles perhaps not what UEFA would have preferred to mark the opening minutes, and quite what the planned re-laying will do to fix the issue is hard to guess.
If O'Neill's decision to play two strikers had the potential to leave Ireland exposed by Italy's five-man midfield, it didn't materialise in the early stages as the two sides were evenly-matched for possession.
Hendrick – who former assistant manager Marco Tardelli revealed earlier this week he'd tried and failed to recommend to Serie A clubs – seemed a man intent upon proving he was worth the high praise.
His was the first chance of the match, as Daryl Murphy rose well to beat stand-in captain Leonardo Bonucci in the air, and Hendrick showed good strength before driving inches wide with his left foot when the space opened up.
Robbie Brady was enjoying the extra space afforded to him in his slot behind the strikers, but it was his set-piece prowess that produced the game's next chance as his corner found Daryl Murphy, and the Ipswich Town striker forced a good stop from Salvatore Sirigu.
There were nervy moments too, as Darren Randolph proved with an early pass to touch, while Shane Duffy put his goalkeeper in trouble with a poor backpass, at the expense of a corner, which James McCarthy did well to clear despite a high boot from Zaza.
There were signs that O'Neill's selection of James McClean was justified, as his pace was causing Andrea Barzagli issues and winger Bernardeschi was offering little help tracking back.
Shane Long was almost presented with a golden chance to open the scoring as, played onside by the fallen Barzagli, he had half an opportunity to shoot from point-blank range before an Italian boot appeared from nowhere to stab the ball wide.
From the resulting corner kick, Brady found Shane Duffy arriving at the far post, but the big Derry defender couldn't crane his considerable neck quite far enough around the ball to direct it back on target.
For the second game in a row, it appeared Ireland's luck was not in with respect to penalties, as McClean appeared to be felled by Bernardeschi (on a rare defensive exercise) just inside the box, but referee Ovidiu Hategan waved away Ireland's incredulous protests.
There were dangerous moments, too, towards half time as Ciro Immobile sought to punish Hendrick's failure to cut out a pass and drove wide, and Duffy needed to be alert to sweep across as the same player looked to complete a swift counter right on the whistle.
And Zaza showed good movement shortly after the break to peel off Richard Keogh and volley Bernardeschi's left wing cross inches over the bar with Randolph struggling to get his hands up.
Long's pace and strength was the bane of Bonucci's night and, after coming close to nicking the ball from him as last man back on one occasion, he beat the Juventus man to a ball in the corner and used the tight angle to force Sirigu into a good reaction stop.
Hendrick was wasteful then as, following a quick free kick, he chose to shoot from Murphy's pass rather than square to a better-placed teammate, and substitute Aiden McGeady warmed his feet with a shot from distance that spiralled to the left.
Again, Italy continued to play their part, and substitute Lorenzo Insigne rattled Randolph's right-hand post with a drive from distance shortly after replacing the ineffective Immobile.
A dive from Bonucci under pressure from Long created a golden opportunity for Wes Hoolahan, on for the excellent James McCarthy, but, with only Sirigu to beat, he couldn't produce a controlled finish and the PSG keeper got down well to stop.
And just when it seemed Ireland's chance had gone, Hoolahan produced the pinpoint cross for Brady to steal into the box unmarked and send the massive travelling support into raptures.
Italy: Salvatore Sirigu; Angelo Ogbonna, Leonardo Bonucci, Andrea Barzagli; Thiago Motta, Alessandro Florenzi, Stefano Sturaro, Mattia De Sciglio (Stephan El Shaarawy 82), Federico Bernardeschi (Matteo Darmian 60); Ciro Immobile (Lorenzo Insigne 75), Simone Zaza.
Subs not used: Gianluigi Buffon (gk), Federico Marchetti (gk), Giorgio Chiellini, Antonio Candreva, Marco Parolo, Daniele De Rossi, Emanuele Giaccherini, Eder, Graziano Pelle.
Booked: Salvatore Sirigu (40), Andrea Barzagli (78).
Republic of Ireland: Darren Randolph; Seamus Coleman, Richard Keogh, Shane Duffy, Stephen Ward; James McCarthy (Wes Hoolahan 77), Jeff Hendrick, Robbie Brady, James McClean; Shane Long (Stephen Quinn 90), Daryl Murphy (Aiden McGeady 70).
Subs not used: Keiren Westwood (gk), Shay Given (gk), John O'Shea, Ciaran Clark, Cyrus Christie, David Meyler, Glenn Whelan, Jon Walters, Robbie Keane.
Referee: Ovidiu Hategan (Romania)
Extratime.ie Player of the Match: Robbie Brady (Ireland).