AS Callum McGregor stood by the side of the Parkhead pitch and chatted to a bevy of newspaper reporters about Celtic’s inspired Champions League win over RB Leipzig late on Tuesday night, opposition manager Marco Rose walked past on his way to the visitors’ team bus.

The German spotted the Scot, slowed his stride briefly, placed a hand gently on the midfielder’s shoulder and said simply, “Captain.”

It was, considering his charges had just suffered their fourth consecutive defeat in Europe’s elite club competition, a classy gesture from the renowned coach as well as a mark of respect.

It was also the closest that anyone in the Leipzig camp got to McGregor during the course of an unforgettable evening for Celtic.

Up until that point, none of them had been able to lay a paw on him or his team mates. The Premiership leaders had produced a breath-taking, dominant, swashbuckling, slick, uplifting display against the Bundesliga high flyers and finished up comfortable and deserved victors at the end of the 90 minutes.   

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The contrast with the lamentable showing against Borussia Dortmund, who Rose spent a season in charge of, in the league phase of the same competition in the Westfalenstadion at the start of last month could not have been any greater.

So how on earth did Celtic go from losing 7-1 against one of the best sides in Germany to beating another behemoth from the major football nation 3-1 in the space of little over four weeks?

McGregor, who also helped his side grind out a commendable 0-0 draw with Europa League winners Atalanta in Italy a fortnight ago, explained what manager Brendan Rodgers has worked on in training at Lennoxtown since their humiliation and outlined just how they had recorded such a famous result. 

“Firstly, with the Dortmund game, we were 5-1 down before we knew it and the game was totally gone,” he said. “They got two penalties, smashed two in the top corner. At this level, if you’re not on it, then you can get done like that.

“You can lose five goals in a half. Dortmund did it against Real Madrid (they went 2-0 up against the defending champions in the Bernabeu in the opening 45 minutes) a couple of weeks ago.

“But the last two performances have been where we want to be. That’s the type of team that we want to be in terms of controlling the game without the ball, not being crazy under pressure and trying to jump at the wrong times. 

(Image: PA Wire) “It was a much more mature performance in terms of when to go, when not to go. Then, when the ball comes inside your organisation, you be aggressive and try and win it.

“Especially when you play at home, you need to bring even more of the control with the ball. That gives you a chance in these games. If you control the ball, you can control the tempo of the game.”

But it was a performance which was months, years even, in the making.

“We have spoken about things,” said McGregor. “We have talked about the process. We are trying to build and build and build. We have had games in the past, against Atletico Madrid last season for instance, where we played well and didn’t quite get there.

“But that was the performance of a team who look comfortable at this level, who look like they believe they belong at this level, who played with courage and quality on the ball.

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“Then, against the ball, we had all the attributes of the Atalanta performance. We sort of married the Bratislava and Atalanta performances and gave a complete performance, so it was excellent.”

McGregor was not the only Celtic midfielder to distinguish himself against Leipzig. Reo Hatate, who netted the third goal in the second half, was exceptional and Arne Engels and Paulo Bernardo also contributed greatly to the win. They bossed that crucial area of the park from start to finish.

(Image: PA Wire) “They were excellent,” said the skipper. “We have spoken about it before. We’ve got so many good options in there and whoever comes into the game is technically of a really high level. You have to be at Champions League level.

“I think it’s probably as good as we’ve been I think in terms of controlling the ball against a top quality opposition. The whole team played their part, everyone was outstanding. I thought we were excellent, especially in the two build-up phases of the game. That really gave us a platform to go and be aggressive.

“I would think it was the best. I can’t remember too many more which were better actually, to be honest. But the last two games, especially here, have been excellent. That’s the type of team that we want to be.

“We want to be on the front foot and play good football. But you have also got to be resolute and defend properly. I think even that was probably even better than the Atalanta performance because I think it was more controlled. 

“So we can be proud of ourselves. it makes it all worth it when you have nights like this and you can go home and you can be proud of yourself. Hopefully the punters enjoyed it.”

McGregor - who has now turned his attention to the William Hill Premiership game against Kilmarnock on the artificial pitch at Rugby Park, a venue that Celtic lost twice at last season – is adamant more is to come in the weeks and months ahead.  

“Again, we’re just learning and building all the time,”  At this level, we’re more and more comfortable. So it should give us brilliant confidence now for the remaining games. But we just keep working and see what we can get out of this league phase.”