An October Sunday lunchtime in Cardiff and a quarter-final against Argentina: this will easily be the most important game that Paul O'Connell never plays for Ireland.

In the six days since the figurehead of Ireland’s rugby revolution left the field on a stretcher, the ovations have just stopped short of calls for canonisation. One of the dominant characteristics of Irish rugby teams over the past decade is that while the players were deadly serious about scaling new heights, they never took themselves too seriously as individuals.

Veterans of the Munster dressing-room, in particular, delighted in putting new arrivals, whether flashy international signings or young professionals, through what, by the sounds of the stories told down the years, amounted to a warm-hearted hazing process. It was at once good fun and merciless.

O'Connell, through his longevity and sustained excellence and old-fashioned leadership and, most of all, by being there winter after winter, in red and green, had earned a respect that ran through both the hemispheres. But the celebrated intensity made him one of the most easily parodied and imitated figures in Irish life and he has become a Gift Grub staple. And every so often, when O'Connell was suited and appearing on a talk show, a hint of the self-mocking, faintly cheesy humour would present itself.

It returned this week when he posted a photograph of gauze, semi-transparent hospital-issue briefs which he was expected to wear into the surgical theatre, citing them as “the highlight of the operation so far”. As items of clothing go, the surgical briefs seem specifically designed to make any wearer feel ridiculous but the image of Ireland’s flame-haired lock – described as ‘inspirational’ and as a ‘leader’ about a million times this week – padding around in toddler-wear is hilarious and succeeded in shifting the mood and attitude towards his injury.

Bent over a ruck

It is, unquestionably, cruel and terribly bad luck that O’Connell doesn’t get to play in the very match that can bring the team into uncharted territory. The mundane nature of his injury was cruel, too: how many times has he been in that very position, bent over a ruck, right where he should be, ready for the next play to develop? He went down and couldn’t get up again.

It took a few minutes for the seriousness of the moment to become clear and by then it was half-time and it began to dawn on people that they had seen the last of him in a green shirt. A friend who scored tickets for Cardiff at the last minute said that the noise when O’Connell was leaving the field as “thunderous”.

Pascal Papé, much maligned this week, was among the French players, to come over to offer his consolations. Everyone stood, as though aware that they were watching greatness departing.

And as if to assert one of the immutable laws of sport – that nobody is infallible – his team-mates came out and gave a storming rugby lesson to France, the very country whose men had dazzled and destroyed Irish teams for decades. So as Ireland celebrated and Cardiff went into party-mode, O’Connell must have had a lonely and conflicted few hours. But he exited in an appropriate way. As the saying goes, he died with his boots on.

The thoughts he shared with the great Donald McRae in an interview that appeared in The Guardian before this year's Six Nations have acquired a wistful hue now. O'Connell was asked to reflect on how far his team might go in the World Cup: "For Ireland to win a World Cup, you need a load of things to go your way. You need luck with injuries because we don't have the player numbers of other countries."

Wide smile

There is so much to be celebrated. What a sporting life. Got the taste for rugby on raw-knuckle winter days spent watching Young Munster with his father: one of the last Irish AIL kids. A big, gangly flamed-haired kid with a wide smile. The training regime at school: 6-8am Tuesdays to Thursdays, 6-7 each evening, 9-11 on Saturday morning and 8-10 on Sunday. And that was just for swimming, the sport he didn’t pursue.

He must have been pushing himself harder than most of the rugby players he watched during weekends in the ’90s. But he had the zeal and the big-boned frame to work with and the seemingly endless appetite for physical conflict which became harder, faster and more unforgiving as coaching and strength technique became more sophisticated.

His international career began much as it ended, with premature departure through injury. O’Connell’s recollection of that debut against Wales, when he came off worse in a collision with Craig Quinnell’s elbow, is both a valorous story and an uncomfortable reminder of the worrying side of rugby. Concussed after the blow, O’Connell played on, scored a try and generally didn’t know what was going on when the team doctor materialised before him and quizzed him about his phone number.

O’Connell saw the clock reading 2.19 and was appalled to realise he would be leaving the field with less than three minutes played. The doctor tried to assure him that no, there was 2.19 left in the half and that he had scored a try, a fact that O’Connell refused to believe. It was only later when he saw the video that he accepted it was true, but it remained a score of which he had no memory.

O’Connell played through 12 battering seasons and crept into the top 12 most capped international players of all time alongside Ronan O’Gara (128) and Brian O’Driscoll (133). The trio were at the heart of the various days of splendour Irish rugby has enjoyed at club and international level over the last decade. Now, for the first time, the show must go on without all three.

At the very end of the RTÉ documentary Hidden Impact, exploring the links between rugby and concussion, Conor O'Shea framed a scenario which got to the heart of the issue: Ireland are in the World Cup final and Paul O'Connell gets a knock on the head on the Tuesday before the game. Does he play?'

It was hardly an accident that he singled out O’Connell as an example. The idea of facing into an occasion – the culmination of an impossible dream – without O’Connell seems like the ultimate example of Hobson’s choice.

As fate directed in Cardiff, it is not a dilemma Ireland will have to face now. If Ireland are to get there, it will be without O’Connell.

Rallying cry

He hasn’t made a tragedy out of The End or declared himself devastated. Instead, he lightened the mood by posting a daffy picture from hospital and will be in among the team this weekend, offering advice and probably a final rallying cry in the dressing-room to the happy few. So Paul O’Connell won’t be earning a cap but he will be all about them on the field. And that may be enough.

It’s an aspect of sport that never fails to catch you unawares. A player like Paul O’Connell comes along and grows up in front of an entire generation and tens of thousands watch the slow metamorphosis from young buck to the gnarled general and he gives so much that total strangers can say of him that they ‘love’ him and in a gruff way mean it and he is such a central part of the Ireland team and Irish sport that everyone can trick themselves into believing that O’Connell, well, he’ll be there forever.

And then the day comes when he isn’t.