THE DAR SEEMED OPEN BUT IT SLID SHUT SO QUICKLY

THE sliding doors moment came in the 22nd minute, that split second when it seemed that Daryl Murphy’s clever jab had crept inside the post.

The long absent Lansdowne Roar, resurrected with such vigour before kick-off and given full voice throughout the opening quarter, roused itself again.

But only for that split second, only until everyone present realised the ball had gone just the wrong side of the upright.

On the touchline, Martin O’neill had burst into that trademark short sprint and jump to celebrate a goal.

The Ireland manager had predicted beforehand that Ireland would have to score two on the night.

With Shane Duffy’s fifth minute goal already bagged, this was the moment.

Except it wasn’t. That split second later, O’neill’s head was in his hands.

Throughout this qualifying group, Irish goal chances were few and far between. O’neill knew how crucial a second goal would have been there and then, how it would have truly shifted the momentum his side’s way in this play-off.

The tide so quickly turns. Seven minutes later Ireland needed to find two more goals, not even one. Mission impossible.

So Ireland will watch on from afar for the fourth successive World Cup and an era draws to a close. John O’shea, Jon Walters, Wes Hoolahan, Glenn Whelan and Murphy have all reached veteran status and are expected to hang up their green shirts.

When they reflect on their heartbreak, O’neill and his players will know they shot themselves in the foot.

The defensive wall that had shut up shop in the three previous qualifiers was undone by costly errors – Harry Arter allowed himself to be nutmegged by Sisto before Cyrus Christie got in a muddle on the goal-line, knocking the ball into his own net.

Then Stephen Ward cheaply conceded possession in midfield. The defence was exposed to a counter-attack finished by Christian Eriksen, his quality finally on display as he rifled his shot into the space between Darron Randolph’s fingertips and the crossbar.

The introduction of Wes Hoolahan and Aiden Mcgeady was O’neill’s last throw of the dice. Ireland had to go for broke, leaving themselves vulnerable to be picked off.

Eriksen was denied by Randolph in the 57th minute, but a left-footer five minutes later, delivered with such finesse, was the fatal blow.

Ward’s 73rd minute mistake, leading to the Tottenham man’s hat-trick, added insult to injury.

All that talk about keeping him quiet, as Ireland had done with Zlatan and Gareth Bale, was only hot air in the end.

But the self-harm was done during the pool stages, too. Having burst into top spot in Group D with 10 points from their first four games, Ireland only gathered three points from the next four games.

The desperately poor draw in Georgia, followed by the home loss to Serbia, required them to win in Cardiff to reach this play-off.

Ultimately, Ireland didn’t have enough quality to merit qualification. Age Hareide’s pre-match confidence proved justified – the Danes, with their superior technical ability, found a way to win.

And the big show will go on without us in Russia. Fans apart, hand on heart, we won’t be missed, while Eriksen will rightly get to showcase his talent next summer.