The call was not unexpected. When Brendan Rodgers, the Celtic manager, sought the counsel of his fellow countryman and former incumbent of the post, Martin O’Neill was more than willing to answer. O’Neill, though, did not offer advice, but rather suggested a philosophy.

“He is long enough in the tooth to know exactly what he wants to do at Celtic and I wouldn’t be in the business of dispensing advice to anyone. Not that they would take it anyway,” said O’Neill, dryly.

“All I said to Brendan was that it is a mighty job. The one thing about it is the glorious intensity of it. That is all. It is not like anywhere else and you know what? He will enjoy every minute of that. You are on all the time. The games are fast and the pressure is absolute and he will thrive on that, I am sure.”

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As soon as Rodgers was formally unveiled as Ronny Deila’s successor, there were parallels drawn between the 43-year-old and O’Neill, who took the Celtic job in 2000. Both men were universally popular appointments, lauded before they had taken a seat in the dug-out; Rodgers brought 13,000 fans out to greet him as he signed the papers for the job, just as O’Neill had attracted a significant number to the car park the day he arrived. Both men were successful too in putting down early markers of their tenure.

For O’Neill, that was a 6-2 hammering of a Rangers side who had finished the previous season 21 points ahead of Celtic. For Rodgers, it was a slow, anxious burn to get the club into the group stages of the UEFA Champions League, where they will now face up to games against Barcelona, Manchester City and Borussia Monchengladbach.

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Critically, as others in the job may testify to, both men have the full weight of belief behind them. “The supporters will be loving it, absolutely loving it,” smiled O’Neill when asked about Celtic sitting at the top table with Europe’s elite again. “You feel that energy. You feel that willingness, the belief in you. The Celtic supporters are special people. They will be right behind Brendan now. I always felt that the Champions League nights and the big European nights under the floodlights were very similar to the games against Rangers – there is just something different in the air for them.

“You can sense the desire and the exuberance from the crowd. The atmosphere is fantastic and while I don’t give anyone any pointers, the only thing I would say is enjoy it. Savour every minute.”

O’Neill himself can appreciate the magnitude of anxiety that the qualifiers give rise to. In many ways there is a compelling argument to make that the greatest riches O’Neill left the club were not the silverware – he brought seven gongs to the club – or the UEFA Cup party in Seville, but the slide into UEFA’s Pot 2 for the Champions League group stages the season after he had left the club.

Given that one of his first remits was to qualify against Jeunesse Esch for a spot in the UEFA Cup, it was quite a distance he took Celtic. So he can understand more than most what went through Rodgers’ mind when involvement in this season’s group stages of Europe’s premier tournament was assured.

“What it is more than anything when you cross that line is an overwhelming sense of relief,” said O’Neill. “It is gruelling, really gruelling. You are playing some of the biggest matches of your season and when you negotiate them successfully what you feel is a sense of satisfaction at having got there.

“You know that if you are in Pot 4 then you are restricted a little because it is always going to be a daunting group. But once you are there you are ready to give it everything you’ve got to compete. Without doubt the group that Celtic have drawn will whet the appetite of the players and especially the supporters and it will be just extraordinary. Those nights at Celtic Park will always live with me. I remember so vividly the night we beat Juventus 4-3 in Glasgow, an absolutely extraordinary night.”

And while part of the reason so much pressure rides on these games comes down to the financial sums that rests on their outcome, O’Neill, who took the Republic of Ireland into the last 16 of the European Championships this summer, was insistent that the cash which the Champions League brings was always secondary to the prestige involved in being part of it.

“I never once went into any of those matches thinking about money and what the money would mean if we got there,” he explained. “I think for every player and manager it is just so important to your personal pride and there is an understanding of bringing that level of prestige to the club that feels very vital to your job.

“We all understand that as a consequence of achieving that then there is a financial aspect to it that brings a lot of stability to the club – but it would never be at the forefront of your mind when you are going should to shoulder with other teams. At this point in time when the deficit between Scotland and England is wider than ever then I can see just how valuable that is now to the club but for the manager and the players the main aspect is what it brings in a very real football sense.

“And the other Scottish clubs do not too badly out of it either so you would like to think that there is some support there for what Celtic are trying to do in the Champions League.”