McCarthy’s battling young team will march proudly into the last 16 of the World Cup if they can overcome Saudi Arabia for even a one goal win will suffice if Germany or Cameroon win the other game in Group E. Ireland will need to win by two goals if this second match is drawn.

It all promises to be a highly dramatic and exciting climax to the first phase of a World Cup competition that has provided extravagant entertainment for Ireland’s army of fans.

And while McCarthy declined to identify the team he will entrust with responsibility for delivering the result Ireland need, he offered a signal to his preferred line-up.

He said: "I thought we played very, very well in our two games here and created lots of chances. The point is we need to take them but I think to change the way you play, the way you’ve played over six years, or five years, and certainly the way that we’ve qualified over a two year period ... to suggest that we change that now is bizarre."

McCarthy threw cold water on the suggestion that he might be tempted to pack the team with still more attacking players as Ireland planned to do something never before done by an Irish team in the World Cup finals and that is to score more than one goal in the game.

McCarthy’s attitude confirmed that the fresh-faced partnership of Robbie Keane and Damien Duff will form the Irish strike force and they will be backed up by the three permanent residents in midfield - Kevin Kilbane, Mark Kinsella and the inspirational Matt Holland.

Clearly McCarthy has a decision to make as to who will play on the right of midfield, whether it is the unpredictable Jason McAteer, the consistent Gary Kelly or the highly promising Steven Reid. Likewise, he must address the fact that full-back Ian Harte has not been in top form but he stone-walled all attempts yesterday to elicit any information about his deliberations.

He said: "We’ve played very well, we’ve had terrific results over two years and I just find it bizarre that anybody would suggest that we would want to change the way we play at this stage."

The fact is that nobody expected McCarthy to take a different line for the 4-4-2 formation is the established Irish pattern for several years, but it is one of this team’s strengths that they have been flexible when the need has arisen.

The introduction of Niall Quinn helped turn the game against Germany and Ireland were operating to a system that was closer to 3-5-2 than their usual when Robbie Keane snatched his golden goal in the 92nd minute.

Anyone looking at the sparkling form of Duff on the left wing and the effectiveness of Quinn as partner to Robbie Keane during the closing 20 minutes must wonder whether Ireland might not be more effective with this combination.

McCarthy showed signs of tiredness and a little testiness at yesterday’s conference, a clear indication that the importance of this match and the huge incentive that it offered was encroaching upon his serenity. He battled gamely, however, to convince the assembled media crew that the significance of the match was being kept at arm’s length.

"Footballers tend to keep a fairly even keel about things and just prepare for the game rather than get excited about what might be. There’s obviously preparations going ahead, has to be in case, hopefully, we do get through, but I’m always cautious about preparing for something that’s not yet happened."

He waved away suggestions that he might monitor events at the game between Cameroon and Germany which will be played simultaneously with the Irish match and said: "I fancy Germany. I think they’re a better side, having played against them both." He was asked whether he expected to feel more nervous than usual in the dressing-room today and said: "Not more than usual, no. No, I think you can say arguably, arguably the biggest game of my career was Cameroon. Not arguably, the biggest game, absolutely. Of all the others, that was the biggest one."

When asked to explain why, he said: "You know full well the reason why, you just want me to say why and I’m not going to do.

"You all know why but as it moves on, the next game is always the biggest.

"I’ve said that before and I think to progress out of this group would be a terrific achievement so this is the biggest game there is, no question as it comes along, it is the biggest game."

He then confirmed the inevitable pressure that he and the players will feel when they strip under Yokohama’s enormous stands and said: "I get nervous before games, I always did as a player. I think it’s healthy to be nervous.

"It means a lot to me. I actually like football and love being involved and I love winning football matches and it’s a fabulous game and I still get nervous."

McCarthy has come a long way in his six years as manager. The routine of having to sit before an assembled group of up to 80 media representatives on a daily basis is not an attractive proposition for anyone in his position, but he handled the responsibility in this tournament with a degree of style.

As always his loyalty to his players was forcibly put and should help to foster the attitude needed to see the job through. When the inevitable question about absent friends was raised he said: “I’ve faith in the 22 players who are here. They’ve been superb.

"I think that they’ve all grown throughout the qualifying competition and it’s not about proving that we can do without somebody else, I don’t think that’s the issue. It’s about proving to themselves that they can play at this level individually and collectively."

Today will tell whether their commitment, their sense of duty, their obvious spirit of togetherness will earn the reward they deserve.