The fact the stadium was packed to bursting point was further confirmation. They could not even do that for the Champions League play- off.
But this was something else, something special, something to restore your faith in football and family.
The #19 Legends Match, to raise money for Stiliyan Petrov's Foundation, the Celtic Charity and the Trussell Trust Foodbank, was all of the above.
Even if young Mr Tomlinson did take ill after being thumped by Gabriel Agbonlahor, forcing the young singer to make his One Direction straight up the tunnel to the treatment room and leaving behind thousands of young female admirers in tears, he was the only one who did not feel better for having been part of the occasion.
Okay, the football was not of the vintage variety, though some of the former players in the Celtic XI looked as though they were.
And, against a team of much younger and fitter individuals in the Petrov XI, it was always going to be more of an event than a contest.
The 5-3 scoreline in favour of Petrov's Aston Villa and Bulgarian-based squad was immaterial.
What mattered was that Stiliyan was there to take part, watched by his family, his friends, and his many, many supporters who have willed him back to health after receiving the shock news 18 months ago that he was suffering from acute leukaemia.
Now in remission, his steroid treatment has made him twice the Bhoy he was when he left Parkhead in 2006 after seven years as a Celtic player.
But then, he has also shown he has twice the character, bottle and heart as he has taken on the biggest challenge anyone could face.
That he has already turned his focus from himself to helping others who are suffering the same devastating condition says everything you need to know about the man.
And it is why so many of his former team-mates were so happy to play in yesterday's game, some clearly better equipped to do so than others with the waistlines ranging from match-fit to won't fit.
Henrik Larsson looked as though he could still play, as did Joos Valgaeren, Bobby Petta, Morten Wieghorst, Pierre van Hooijdonk, Jorge Cadete, Tommy Johnson and Lubo Moravcik.
Others have not fared so well, but were happy to give everything they still had.
Larsson did get on the scoresheet, from the spot, along with van Hooijdonk and Hollyoaks actor, Warren Brown.
Dimitar Berbatov, still playing for Fulham, grabbed a hat-trick for the opposition, with Martin Petrov and former Westlife singer, Nicky Byrne, the others on target.
It was perhaps surprising that only Tomlinson and Stevie Graham, who plays Al Capone in Boardwalk Empire, picked up injuries which forced them off, though there are sure to be many of their team-mates struggling today.
They can at least feel good about the fact they played their part in raising a shed-load of money for very good causes.
And Celtic XI manager, Martin O'Neill, believes it summed up what Celtic FC, and their fans, is all about.
"Stiliyan has got a great family behind him, and the medical staff were terrific, too," said O'Neill, no stranger to the fight against cancer after helping his wife, Geraldine, win her battle.
"He has had lots of support, and I think that was very important to him. He said that himself, and today it just manifested itself.
"Really, it's phenomenal."
O'Neill - who took Petro v from Parkhead to Aston Villa in 2006 for a then-record £8million - added: "I had seen Stiliyan a number of times and he wasn't in great shape.
"He was fighting strongly and, of course, I knew the professor who was working with him at the time (through O'Neill's wife's illness). So, I knew he was in good hands. But you still need to battle through it.
"He asked me a number of weeks ago about the game he was helping organise with Celtic. It thought it was a fantastic idea, and I am just astonished at the reception.
"I really shouldn't be, but it was absolutely fantastic and he deserved it."
O'Neill added: "I've got enormous respect for him and his generosity in every aspect of his life is phenomenal."
A generosity which will now enrich the life of many, many others when they need it most ...