CARDIFF, Wales -- Ireland secured the win they so desperately craved in Cardiff but at what cost? The Millennium Stadium roof was almost lifted from its fixings as Conor Murray dived over to confirm victory and a quarterfinal against Argentina, yet the scars of their brutal clash with France could well cause Joe Schmidt discomfort for as long as they remain in the tournament.

Ireland were the better side for long periods, the passion of their support in the stands and back home transmitting itself onto the pitch. And with the post-match prognosis on Peter O'Mahony a positive one, the price they paid in Cardiff may not end up being as hefty as first feared.

Paul O'Connell of Ireland is stretchered off © Getty Images

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Three frontline players -- Jonathan Sexton, Paul O'Connell and O'Mahony -- were forced off through injury, while the citing commissioner will probably want to take another look at an apparent punch by Sean O'Brien on Pascal Pape.

Ireland might be able to cope with the loss of one of that quartet -- although you feel their captain and fly-half are almost irreplaceable -- but all four would likely prove an impossible task. The news, relayed by head coach Schmidt, that O'Mahony was walking around the dressing room after the final whistle and that Sexton was eagerly planning for the Pumas should therefore cheer Irish supporters.

"The update I can give you is it doesn't look great with Paul, it looks like an upper hamstring," Schmidt said. "But we're going to have to wait until tomorrow to get that scanned just to make sure the inflammation has decreased a little bit.

Ireland's Jonathan Sexton pulls up injured © Getty Images

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"Jonny it looked like an adductor to me but that's not the learned eye of a medic so we're probably gonna get Jonny scanned tomorrow and Peter O'Mahony as well. Pete actually didn't seem too bad so we're hopeful."

He added: "I've spoken briefly to Jonny and he's already talking about next week. So I'm not sure whether that means he'll be playing next week, but he's never usually short of advice. It's probably Paul who worries me the most of those three."

When quizzed about O'Brien's alleged indiscretion, Schmidt did not shy away from the issue. "I truly hope not," he said when asked if he expected a ban. "I think he was being held at the time. I don't think he was looking at the player but it's not for me to determine."

Should O'Connell become the latest player to have his international career ended prematurely by injury at the Rugby World Cup, it would be a cruel blow for a giant of the game. The enormity of the situation appeared to be summed up in Cardiff as Ireland fans leaving their seats for half time paused, turned towards the pitch and watched the lock being carried off, possibly for the final time.

As the Irish captain was taken away from the pitch on a stretcher applause rang out around the Millennium Stadium. Fans of both Ireland and France joined in as they realised the magnitude of what was unfolding near the halfway line, attempting to give the former British and Irish Lions skipper a fitting send off.

France captain Thierry Dusautoir led the tributes after the game. "I don't know his injury but it's true that it's always been hard games against him, he's a warrior. It's true that I have a lot of respect for him and after Brian O'Driscoll, it's a big player who's leaving the Ireland team."

Schmidt can at least take solace from the fact that, in many respects, this was a win that owed itself to the impact made by those who came off the replacements bench in Cardiff. Iain Henderson slotted in seamlessly for O'Connell, even though he had not been earmarked for that role, and when France sensed their chance in the second half those fresher legs helped steady Irish resolve.

Ian Madigan played his part too having come on for Sexton with little more than 25 minutes gone and this was a performance that suggested he could finally be settling into life on the international stage. Watching the Leinster playmaker can often be a frustrating experience but here he immediately injected energy into Ireland's attacking play.

One moment in the second half highlighted the fly-half's ability, as he dinked a weighted chip over the French defence for Robbie Henshaw to chase. It is the sort of skill that you would expect his French counterpart, Freddie Michalak, to attempt and that it came off hints that the combination of Madigan and Henshaw could bear fruit for Ireland.

Schmidt described Madigan's performance as "assured" and a result of the hard work he puts in away from the pitch, but there is no doubt Argentina would prefer to face an Ireland team with the Leinster man rather than Sexton at No.10. Not least because of his perceived weakness under pressure from the kicking tee.

Those questions are for another day, however, and as Irish fans streamed out of Millennium Stadium they did so buoyed by the elation of a hard-fought, and richly deserved, victory. They will be happy to hear, too, that their support played a part.

"I've been really lucky in my career playing some special games with Leinster, Ireland and the Lions but that atmosphere surpassed everything," Jamie Heaslip said. "At times our lungs were bursting, legs were on fire. To get a break in the game and hear them chanting, you look up and all you can see is green. It gives you that '16th man' lift."