Five things we learned as Ireland crashed out of World Cup after Christian Eriksen's Denmark masterclass

The Danes ruthlessly ended Irish hopes of reaching Russia in Dublin

Christian Eriksen was on sensational form at the Aviva Stadium (Getty)

Eriksen’s class tells on the night

It always seemed that, even with all the talk of ‘anti-football’, a certain player’s class would ultimately tell in this tie.

Denmark may be a better side than Ireland but that is only because they have Christian Eriksen, a truly excellent player on the verge of becoming one of the game’s superstars.

Tottenham Hotspur’s creator-in-chief turned executioner at the Aviva, exquisitely finishing off the counter-attack that gave Denmark the lead with a shot placed perfectly to clip in off the underside of the bar.

Two more followed - a shot beautifully arced out of Randolph’s reach to effectively book his side’s ticket to Russia, then a snap-shot, ruthlessly despatched, after Stephen Ward’s botched clearance.

The World Cup would have been less of a spectacle without him.

Opener vindicated O’Neill’s initial set-up

When the Republic of Ireland’s teamsheet was released, it was clear a place at the World Cup had not tempted Martin O’Neill to revise his principles.

As usual, it was a pragmatic selection, with the intention of limiting the visitors and taking half chances rather than looking to come out and play. As usual, there were complaints from Irish supporters.

Yet even if the final result was not the one either they or O’Neill wanted, Shane Duffy’s opener was a small vindication of the manager’s initial set-up. Ireland capitalised on the first error their opponents made and in doing so, gave themselves a huge opportunity to progress.

The hard bit had been done. From there on, it was simply about repeating the defensive performance seen in Copenhagen. Ireland, unfortunately, could not do that.

Goal scoring issues come back to bite Ireland

No group runner-up in Uefa’s qualifying section scored fewer goals than Ireland, not one of them had fewer shots on target than O’Neill’s men. At some point, whether here or in Russia, this would hurt them.

When Eriksen gave Denmark the lead, the hosts needed to end the night with three goals on their side of the scoresheet. The only time they have notched so many in a competitive international under O’Neill was against lowly Gibraltar.

It just never, at any point, felt likely. Once Ireland needed to chase, they simply had too few answers to the questions Denmark posed. Wes Hoolahan and Aiden McGeady are not reliable options to change an international football match anymore.

It raises questions about where this side goes next, with a lack of young talent emerging through the ranks, especially in creative areas of the pitch.

Meyler’s pre-match comments proved wrong

“They are a very good team, very good players, but they don’t have the character and the heart and the desire that we have.”

It’s never wise to make such comments about your opponents when they are on the verge of one of the biggest occasions of their professional lives, but David Meyler’s frank pre-match assessment of those in Denmark’s ranks sounds even sillier now.

The Hull City midfielder was right in one respect: this Irish team has shown much character over the years. Yet the Danes proved they have just as much resolve with their composed and confident response to Duffy’s opener.

Instead of panic, there was ideas. Instead of hopeful percentage play, there was invention. That’s often enough to overcome the most ‘heart’ and ‘desire’ any team can muster.

O’Neill’s task now is to find a Plan B

Despite the disappointment, it is worth noting how well O’Neill has done to get a tune out of this group of players, limited as it is.

Ireland have a clear and defensible ‘Plan A’ that until the half-hour mark, looked like it would be enough to reach a second consecutive tournament. It was only exposed first by a spot of bad luck and then, repeatedly, by a slice of genius.

Unfortunately, and especially for those sides not blessed with a player like Eriksen, international football often requires a Plan B.

O’Neill will have a free summer in which to find one.