O'Neill's warriors laid down an early marker in Cardiff
On a night like this, the superstitious among us were happy to search for omens everywhere.
And Scotland's draw with Slovenia on Sunday carried infinitely more weight than a brace of joyful magpies.
Gordon Strachan's misfortune presented Ireland with a golden opportunity that recalled the fateful night in 1987 when Hearts player Gary Mackay did Ireland a favour by scoring the goal in Sofia that ensured Jack Charlton's team went to Euro 88 and not Bulgaria.
Surely this was a lucky break that couldn't be spurned?
A win would see Ireland in the play-offs. At least.
And if Georgia could defeat Serbia, then we'd all be swotting up on our copies of Russian for Dummies. "Davajtye poznakomimsya! Nostrovia!"*
For all the bluster, mind games and poor-mouthing, Ireland were facing a Wales team that didn't have Gareth Bale on the pitch.
Head to head, Ireland's gaffer had the edge in terms of experience on the Wales manager Chris Coleman.
But trepidatious Irish supporters were uneasy that Martin O'Neill's unpredictability might conspire to make things difficult for the Boys in Green.
This being the equivalent of a league six-pointer or a cup tie, O'Neill appeared to abandon any possibility of Ireland winning by skill and guile, opting instead for a team that seemed intent on asserting itself physically.
There were shades of assistant manager Roy Keane's playing days about James McClean's fifth-minute tackle which upended Aaron Ramsey.
If Ireland were laying down a marker, it was reinforced on 32 minutes when Sunderland's Jonathan Williams had to come on for a dazed Joe Allen, who'd wound up as the streaky bacon in a Meyler-McClean sandwich.
And you wondered if O'Neill's plan had been designed to consign players in red shirts to seats alongside Bale in the director's box.
With the scoreboard showing 0-0 at half-time, it seemed that Martin O'Neill had decided to play a game of high-stakes poker on the most important night of his career as an international manager.
The home side had failed to assert themselves and now the stage was set for Ireland to up the ante, perhaps by adding the play-making guile of Wes Hoolahan to create a few chances.
Initially, Wales seemed to have more to play for early in the second half.
A James Chester header from a corner on 51 minutes hit side netting. Two minutes later it took Darren Randolph's strong right hand to keep the ball from rattling the net from a Hal Robson-Kanu header when he directed it over the bar.
But first blood came from a James McClean scorcher, on what's described as "his bad foot", after sterling and persistent work by a determined Jeff Hendrick along the sideline.
One-nil to Ireland.
As tackles became even more full-blooded, Slovenia referee Damir Skomina adopted a generally unfussy role.
It was a night of old-school Ireland heroics in Cardiff. Backs to the wall, from one end of the pitch to the other, Ireland drew on the reserves of courage that have been a hallmark of the Boys in Green for generations.
Wales piled on the pressure in the closing stages but not even lusty choruses of support by the home supporters seemed likely to break down the massed Ireland defence.
When the Fat Lady sang in Cardiff last night, the song she sang was that Ireland were through to the World Cup play-offs.
"When it comes down to one game the spirit in this group, we can do anything," said Jeff Hendrick on pitch side afterwards.
Now come the play-offs.
* Translation: "Howya! Let's have a pint!"