...and they did. David Moyes can afford to smile a little after his United side got noticeably stronger over 90 minutes. That's not happened enough times this season...
As long as there is both football and human weakness, there will be allegations of match-fixing. But a decent start would be an independent, national body...
There are football upsets that end in acrimony as players trudge from the pitch complaining about the referee, the playing surface and the fact that the sun was in their eyes. While also going out of their way, at the same time, not to shake hands with their conquerors. That infuriates me.
And then there are upsets that end in one of the finest players the game has ever seen telling reporters that the atmosphere at Celtic Park on Wednesday evening was "a marvel and an example". And Xavi, the captain of beaten Barcelona, was not alone in his praise of the Scottish champions. In the aftermath of defeat, Barcelona put out an official Tweet that read: 'Congratulations to @celticfc for well-earned victory a day after their 125-year anniversary.'
Aside from the blue half of Glasgow, there aren't many people that have a bad word to say where Celtic are concerned. And they are a player's dream testimonial side because they always bring a huge following and there's never any hint of trouble.
The same cannot be said for the players and fans of other sides, as we have seen all too recently. Whenever I am on the winning side against one of the biggest teams in world football, it is striking how little in the way of humility and grace is on offer as the final whistle blows. Arsenal, for my money, are the worst, epitomised by Arsene Wenger, who refused to have a drink with our manager afterwards - as is the custom in the Premier League. And not just the once, either.
But everyone and every team are different. I remember playing a leading continental side and being taught a lesson in how to play football. And each time we'd win the ball back, the dispossessed player taught us how to cheat - usually by rolling around holding his face.
Yet after the game, they could not have been more charming and friendly, with a lot of embracing and double-cheek kissing going on. Three of their players asked for my shirt and I had to ask "Paolo", one of our foreign imports, to ask one of them why they were so desperate for my shirt, particularly as I was fairly certain that none of them had any idea who I was.
Paolo told me that, during the game, I had pulled off a stepover followed by a backheel that had put our striker clean through on goal. Apparently, this had impressed our opponents hugely.
And that's the thing with football. It costs nothing to be gracious. There must be a reason why I remember that moment as vividly as any other in my career. In fact, it is one of the few shirts that I have kept hold of and every now and again I'll wear it out and about.
There's something not right about grown men wearing football shirts away from the stadium but I don't really care because I feel very humble every time I put it on.