Celtic celebrated their 125th anniversary with a bit of style. Beating the best team in the world at Celtic Park, Lionel Messi and all, was a fitting 90 minutes to enjoy the milestone back in 2012.

While it was a landmark result for the club, the noise and energy that surrounded Celtic and their 2-1 defeat of Barcelona that night simply served to underline a sense of isolation for Callum McGregor.

The 23-year-old midfielder had undergone a hip operation in the build-up to the game and was still recuperating at home.

“I was still on crutches so I was told I couldn’t even go to the game because it was too dangerous,” he said. “So I had to watch it from the couch. It was mixed feelings for me. I was delighted to see the team get such an amazing result but you just feel out of it in a situation like that.

“Tony [Watt] and I had played together in the same development team and I was made up for him that night. It was like a fairy tale, coming on and scoring the goal that he did.

"It was even what it done for the team and the club after the game. The place was buzzing for weeks.

“I remember watching the game and promising myself that not only would I get back fit and stronger than ever but that I would get to that level, a lever where I could play against teams like.

“So here we are. I have had a wee taste of the Champions League this season and like everybody else, I am desperate to start. I don’t know whether I will or not because that is obviously a call for the manager but I hope that I am involved at some level.”

Barcelona could be without Messi on Wednesday night, after the striker missed the Catalan’s draw with Malaga this weekend due to illness.

Whether he starts or not, however, Celtic’s task in maintaining their slim hopes in the UEFA Champions League require the kind of result that caused such a shock four years ago.

If the 7-0 defeat in the Nou Camp in the opening game of Group C is still the cause of cold sweats in the dead of night for some of the Celtic players, McGregor is well aware that they need to banish any fear as they go head to head with Barcelona.

“It is funny,” said McGregor. “You grow up idolising some of these players. You see them playing in a glamorous league for one of the great football institutions but when you are on the park it is 11 v 11.

“I can’t imagine that too many people will give us much of a chance – but that isn’t the way that we see it. We are not silly. We understand how hard it is going to be but what would be the point of playing football if you had given up before a ball was kicked?

“If that game four years ago shows anything it is that shocks can and do happen. It is up to us to try and produce another one.

“If you look back at our record at Celtic Park, we are capable of going toe-to-toe with teams. That Manchester City game here was incredible. The noise and the passion of both teams was amazing but you could sense the crowd willing us on.

“Hopefully they can produce that level of noise again and we can produce that level of performance.”

McGregor came through the ranks at Celtic and was frequently on ball boy duty during the Champions League night.

He was cast as the villain of the piece in Germany when he missed a late chance to give Celtic all three points against Borussia Monchengladbach, but in fairness to the midfielder the Parkhead side had lived dangerously in that opening period when the game could have been away from them.

As the Hoops face up to the penultimate date of their campaign, and their last home game in the tournament, McGregor is optimistic that there will be no-one coming off the pitch with any regrets.

“I think we are ready to give our all,” he said. “The manager is meticulous in his preparation. Obviously in a game like this against a top team there are things that can happen but hopefully we can go out and give a good account of ourselves.

“It has been brilliant to be in the Champions League this season but I think the whole thing for us wasn’t just that we were in, but that we wanted to do well too.

“We have had a really tough group. We have two games left to make an impact and then see where we are. But I think we are definitely a better team for the experience of being in the competition.

“We would like to think that it’ll stand us in good stead going forward.”

Moussa Dembele, of course, has shot to the fore in these games for Celtic this season. The striker missed a penalty in the Nou Camp but proved a serious handful for Manchester City to cope with.

And McGregor believes that the Frenchman can be the man capable of nicking any half chance that Celtic get.

“He is powerful, he is fast, he is comfortable with both feet and he seems to be the calmest player on the park at times,” says McGregor. “He has been inspirational for us this season.

“Hopefully if we can get the ball to him in the box then he can do a wee bit of damage.”