Comment: Ireland are better than O'Neill thinks they are as managerial hara-kiri ends World Cup hopes
Backs to the wall and only one way out. For the Republic of Ireland, the exit door.
In the end, the Republic finished the game with three centre-backs and two strikers and the rest filling in where they could.
It was almost managerial hara-kiri, an exercise in which the bench seemed to absolve themselves of any control over the unfolding rout.
Christian Eriksen was thus allowed to roam the Dublin 4 turf as if it were the backyard of a docile child, rather than a hostile visitor.
Eriksen symbolises a side who have transformed their playing style and also radically redefined themselves in how they utilise their best asset.
The Republic, in contrast, regard their best footballer as an awkward adornment and any pretensions to a passing game, even if merely to take pressure off one's own defence, with arrant suspicion.
That belief was cast into cold relief on a night drizzled with regrets at how a collection of men, who could find such expression on the fields of France, have been ignorantly muzzled.
In the end, despite an early lead, the Republic were asked to play a game that was beyond their limitations because, unlike with their clubs, they have been denied the chance to play it.
All of a sudden, the cult of miraculous motivation trumping precise preparation and naming teams an hour before kick-off seemed utterly redundant.
It had started so promisingly, perhaps surprising the Republic themselves more than Denmark, Shane Duffy snatching a lead.
The next 84 minutes yawned like a lifetime.
The Republic were much more energetic in their hustling and harrying; more than that, they showed the guile and invention which all know these top-class professional players display every week for their clubs.
A second goal was required, as O'Neill had suggested; instead, the Danes reached that number before them, first after a stunning lapse in concentration at a corner when Harry Arter was left isolated against two men.
When one of them, Pione Sisto, nutmegged him, Arter's gathering collection of colleagues in the box couldn't prevent the sloppy concession.
The Danes get a marvellous second goal through that man Eriksen.
Just as we think it wiser to retreat James McClean, to at least occupy the middle, he bursts down the left on the break with Brady and creates a chance for the outnumbered Murphy. It is but a momentary rebel yell.
The Republic's full-backs are now repeatedly exposed by the narrowness of a midfield who aren't comfortable enough in their own positions to influence the proceedings.
They, and their manager, pine for the promise of half-time reinforcement and, either a reminder of who is supposed to be playing where or what they are supposed to be doing there.
Ultimately, O'Neill opts for a double-switch with Hendrick surviving the cull as Aiden McGeady and Wes Hoolahan are brought in.
Now they are 4-2-3-1. The energy and enthusiasm of the switch offers early exuberance and the Republic go close to halving the two-goal tally they require for progress.
Too late in the day, the Republic require a style to progress with which they have never been trusted to implement.
Denmark radically shifted their intentions a good while back, despite the image of their manager as being a relic of the Norwegian stone age.
Our old friend Sun Tzu taught us that one needs to know ourselves as much as the enemy.
Sadly for the Republic, their manager has not consistently given them the encouragement to discover that they are much better than he thinks they are.