Last night, 55,000 Hoops fans followed the crooner's lead. Tears of joy flowed as the Hoops defeated Spartak Moscow 2-1 to book their place in the last 16 of the Champions League.
The tension of the occasion was finally broken just nine minutes from time when Kris Commons smashed a penalty won by Georgios Samaras into the net off the underside of the crossbar.
Neil Lennon could not bear to watch as the midfielder stepped forward to hold his nerve and fire his team into the draw on December 20.
Those final nine minutes will live long in the memories of those who attended and the millions who tuned in on TV as they anxiously tried to watch this game through the cracks of their fingers, while also following events in Barcelona where a goal for Benfica would have sent the Portuguese club through in place of Celtic.
It may not be until this morning that the players and Lennon will truly believe what they have achieved.
With 10 points from their six games, it would have been cruel if they were parachuted into the Europa League.
But they are in the big one, and £5million more big ones will be heading the way of the club's coffers as a result.
The next European game to be staged at Parkhead will be a last 16 home leg against another of Europe's giants.
None of them will fancy this gig. But no matter who that is, the occasion will struggle to evoke the kind of see-saw of emotions which filled the stadium last night.
Celtic's 150th European Cup tie also marked the most important team selection made by Lennon in his two-and-a-half years as manager.
With the promise to go for it, he elected to go with the goal threat of Samaras, Commons and Gary Hooper from the outset.
Joe Ledley was entitled to feel unfortunate that he could not command a starting place, with Scott Brown partnered in the centre by Beram Kayal in the absence of the suspended Victor Wanyama. Balance and threat were Lennon's priority.
With Aiden McGeady not yet 100% fit after his recent injury, he was also reduced to the role of substitute for the Russians in the opening 60 minutes.
Spartak had shipped 12 goals in their last three outings, and interim coach Valery Karpin reckoned the best form of defence was to try and attack, which his team did with pace and creativity through Dmitri Kombarov, Emmanuel Emenike and Kim Kallstrom.
Anyone who thought that, with European football over for the season after this game, the Russians would simply go through the motions were quickly forced to change their opinion.
Which was why the first goal was so important, both in terms of spiking Spartak's guns and firing Celtic's confidence.
Samaras' driven ball forward from halfway on 21 minutes should have been simple for Jaun Insauraralde to mop up.
But the big defender is not having a good time of it of late, with him being sent off when Celtic won in Moscow, and again seeing red in last Friday's defeat to Zenit.
He allowed Sami's pass to slide under his foot, and Hooper needed no second bidding to step forward and unleash a low shot from 20 yards which flew past the advancing keeper, Sergei Pesyakov.
Unfortunately, there were still 69 minutes to go, and it took Spartak only 18 of them to draw level.
The powerful Emenike held off Nigerian internationalist team-mate Efe Ambrose, along with Kelvin Wilson and Kayal before passing to Ari lurking on the right-hand side of the box.
The player caught offside more than anyone else in the competition this season for once had remained onside. He also remained composed and chipped the ball over Fraser Forster and towards the net.
Wilson got back to try and head clear from under the bar, but the best he could do was send the ball into the roof of the net.
Given the possession Spartak had enjoyed in the first half, going in level was no more than they deserved. But with it all still to do, and now only half the game in which to do it, the pressure on Lennon and his players had reached critical point.
The news Benfica were pummelling a makeshift Barcelona side in the Nou Camp did not help, albeit the Portuguese, too, were being held.
The question Lennon had to answer was: Should he go all out for a winner, and risk being picked off, or play it cagey and hope Barcelona – with Messi then not on the field – could beat Benfica, in which case the point they had would be good enough?
What the increasingly- anxious crowd got was a mixture of both, with Samaras hitting a post with a volley, Ambrose sending a header just wide from a corner and Charlie Mulgrew seeing another header tipped over by Pesyakov.
The set-pieces were, in general, a big disappointment on the night, Spartak's vulnerability to high balls into the box nowhere to be seen.
But thanks to Commons keeping his cool, and Spartak being reduced to 10 men late on when Kallstrom collected a second yellow for a bad foul which saw the penalty hero stretchered off, another piece of Celtic history was written.