Shane Long can get up off canvas to land a telling blow for Ireland
O'Neill facing crucial call between battling Murphy and unpredictability of Saints striker
They say the last attribute a great fighter loses is his punch, his capacity to settle everything in one moment of concentrated thought and power.
If the same was true of strikers, Martin O'Neill might be in less of a dilemma before the World Cup play-off action in Copenhagen when he comes to choose between Shane Long and Daryl Murphy.
Certainly he would have to consider the old maxim of the square ring, believe that even when so much has been discouraging for Long over some barren months he still retains the ability to do something quite exceptional.
Rewards It is in this light, and against the weight of the rewards that would come with success against Denmark, that the case for Long is strongest because on the face of it the issue is plain enough. It's between Murphy's heart, his dogged persistence in the front line, and the more sophisticated attacking instincts of Long.
Everyone knows, and not least a growing army of support on the Irish terraces, what Murphy has to offer. He will battle and fight for ever. He will be filled with a deep competitive optimism.
But will he get to the places that Long (pictured right) might, less predictably, more instinctively?
The question concerns limited certainties and uncharted possibilities. It's the difference between application, utterly guaranteed in the case of Murphy, and maybe a moment which is decisive and is borne not of effort and guts but of a refined, acute hunch, something that Murphy, for all his virtues, might never have in him.
For the Ireland manager, though, there is an additional worry.
While everyone remembers Long delivered one of the most memorable killer blows in the nation's football history, the goal against world champions Germany that cleared the way to the 2016 Euro finals, there is a strong suspicion that O'Neill has never been convinced that he is indeed a natural-born scorer.
A much quicker, more dynamic player than the worthy Murphy, who scored two goals against Moldova before the vital triumph over Wales, while his rival was missing a series of barn doors, and scored twice for his Championship club Nottingham Forest last weekend, Long is inhabiting a wasteland of missed opportunities.
He has gone without a goal since February. It is not so much a professional burden as a pitiless statement of growing futility.
And with each chance that passes, Long is bound to reflect on the words of the Ireland manager shortly after he took office.
Said the man whose football thinking was influenced by one of the most fertile scorers in the history of the game, his old Nottingham Forest manager Brian Clough, "Shane is capable of scoring a great goal but what I want him to be is a great goal-scorer. I think he has to get into a mentality to think about scoring goals - he has to be able to do that.
"He's getting opportunities, coming on as a sub and scoring and then he starts a game and maybe doesn't finish the match. Whatever you say about him, Robbie Keane comes out and plays a No 10 game, quite often he's done it at Tottenham and other clubs but he can still get into the penalty box to score a goal because that is what he feels is his major contribution. Shane has got to get into that mentality."
Two years on, and at the age of 30, Shane Long is still in pursuit of that lost chord to a game which in so many ways is filled with an impressive cutting edge and an excellent vision for dangerous possibilities.
But then he is also mocked by his failure to score with the kind of consistency his talents have so long demanded.
He has scored 17 goals in 71 games for Ireland - against Murphy's three in 27 - so in neither case can O'Neill afford the luxurious thought of being equipped to open the scoring floodgates.
What he has to do is make one of the most crucial decisions of his career, he has to balance the solid, if less than thrilling sureties offered by Murphy against the chance that Long will unveil a moment to place alongside his conquest of the world champion Germans.
Roy Keane, in his role as the ramrod of the Irish team, recognises the underwhelming case Long has made for himself at Southampton over a critical period, but he seems ready enough to accept the player's potential to produce something remarkable.
Before the taut game in Georgia, however, Keane agreed that Long could have done more to establish his position at Southampton.
"As much as we look at managers, I always say the player has got to look at himself … got to look at the man in the mirror. It doesn't seem to be happening for Shane at Southampton at the moment but does that mean he would be reluctant starting for Ireland, wouldn't bring to it everything he had to offer. Obviously not."
There is the agony for O'Neill before he sends out his team in Copenhagen. He has to speculate on the chances that from deep within his football nature, Shane Long will find something that, for all its recent elusiveness, can from time to time shine like a diamond.
He has to wonder if, like a champion fighter down on his luck and form, the man from Tipperary can find some impetus with his back to the ropes.
Daryl Murphy, O'Neill knows well enough, will battle until he drops. But does he have the same potential to deliver, in very good football company, a knockout blow?
There, perhaps, lies the difference between a brave and hard-fought challenge and a place in the World Cup for the first time in 16 years.