O'Neill must redress the balance between two old Celtic warriors
Maybe Ireland are right to believe that emotional wounds sustained by Aiden McGeady under the command of Gordon Strachan at Celtic Park might just provoke an impassioned and decisive performance at the Aviva Stadium tomorrow.
Certainly the Scotland manager knows enough about McGeady's capacity to cause damage on the field to avoid reviving the personal friction which once brought them nose-to-nose in a dressing room confrontation.
McGeady's potential to erupt into serious virtuosity indeed may be Ireland's best chance of regainingmomentum after the body blow of defeat in Glasgow. And if it happens Martin O'Neill will have some reason to be grateful for the former Celtic player Mark Wilson's recounting this week of that old but apparently still smouldering episode.
"It is fair to say Gordon and Aiden didn't get on too well," Wilson revealed. "It was a clash of personalities."
However, if this is one possibly dangerous consequence of Strachan's fiery brand of leadership it is unlikely to cast any serious doubt about the wisdom of the former Manchester United midfield general's appointment by a Scotland with so many reasons to believe that a great football tradition had pretty much died on the vine.
Strachan may still strain to recognise in the blue shirts the kind of world-class quality that down all those years was a such a staple of the Scottish game, but so much easier to note is a sense of some of the old passion.
It was a hauteur once expressed memorably by Denis Law when his newly capped Manchester United team-mate Nobby Stiles offered his hand before an international game. Law, cold-eyed, declared, "f… off you little English bastard."
These are early days, perhaps, but O'Neill has already recognised that Scotland's vital home victory was a triumph of motivation which he now desperately needs to produce on Ireland's behalf.
The concession of this reality has shone through O'Neill's build-up this week, not least when he said, "We want to play well under pressure, to throw the shackles off and play as strong as we can. If we do that, we can win.
"Of course there will be tension around the place but the same will apply for Scotland as well. If you were to ask my players, they would all want to be playing. They would all want to be starting the game - and that's encouraging."
Encouraging? Elementary might be a better way of saying it.
So far Ireland's great achievement in this campaign, apart from staying in touch with potential involvement in the business end of the process, is a certain level of sangfroid.
Conjuring a late goal against World Champions Germany was remarkable enough. The second-half recovery against group leaders Poland was impressive, even while begging questions about the timidity of their start.
With such key players as Glenn Whelan, James McCarthy, Marc Wilson and Wes Hoolahan available again, and Robbie Keane back from football's American frontier, O'Neill needs above all convincing, game-shaping early conviction. He needs someone like Seamus Coleman to remind us why so many believe he is destined join the elite of the world game. He needs to look out on to the field and see evidence of genuine self-belief. Only this will give Strachan's Scots reason to pause and, perhaps, let in a little self-doubt.
That element, which has been a worrying feature of Ireland's recent profile, was certainly not in too much evidence when Scotland went to the fortress of Dortmund and required Thomas Muller to score twice to kill off a spirited second-half recovery - and then escaped from Warsaw with a point after a splendidly combative draw.
Both performances, and the one which brought victory over Ireland, bore the imprint of Strachan, a player whose fine skill was always married to a fierce confidence in his own powers. He carried that style into his time at Celtic and made his lack of impact at Middlesbrough as surprising as O'Neill's deflated exit up the road at Sunderland.
It is as though two highly respected football men, Strachan at 58, O'Neill 63, are tomorrow in search of not only the best of their teams but themselves. For the moment, it has to be said, Strachan has displayed more buoyancy.
Enough, certainly, to inspire a fulsome if somewhat contradictory vote of approval from the Scottish FA's chief executive Stewart Regan.
However, before declaring that Strachan had done as much as Scottish nationalist leader Nicola Sturgeon to rally the nation, he said, "It's far too early for talks (with Strachan on a possible new contract) as we concentrate on qualification for now."
Translation: So far so good but a florid quote or two is as much as he's getting until we qualify for our first major tournament in 18 years.
Strachan no doubt merely shrugs off such reminders of the mores of football, as he did when Alex Ferguson dragged his feet in contract talks before the player left for a brilliantly defining phase of his career with Leeds.
After serving Ferguson so well, if sometimes rebelliously at Aberdeen and Old Trafford, he drove to Yorkshire with scarcely a backward glance.
A player of less craft and professionalism, might have been lost in the long-ball game that brought the title under the management of Howard Wilkinson. Instead, Strachan formed a brilliantly effective duo with fellow Scot Gary McAllister. It was the kind of superior pragmatism that is so firmly stamped across Scotland's current nursing of limited but impressively marshalled talent.
O'Neill has a similar reputation for an intelligent understanding of available possibilities but going into tomorrow's game there is no doubt that it is in some need of refurbishing.
Like Strachan's, his credentials were far too strong to be too seriously undermined by some misadventure in the North-East of England but sometimes there comes to a career, however distinguished, a game which might have been set up to examine a football man's enduring (or not) feel for what he is doing and what he must create. In these terms it has to be said that Strachan arrives with a somewhat firmer tread. Certainly he appears to have created the greater sense of purpose in his team.
How odd it would be, then, if there was cause to say that his greatest contribution to such a vital game had proved to be the old one of trying to concentrate the mind of Aiden McGeady.
Maybe it goes without saying that Gordon Strachan would probably be the first to see the irony.