“You’re playing against teams that have quality all over the pitch,” he said. “Any little mistakes, mental errors and things like that, which an inexperienced group make, are punished. That’s what the Champions League is all about.

“I’m not necessarily saying we’re inexperienced, but we did have a lot of players who were making their Champions League debuts, myself included. The only guy who’s got a ton of them is probably Joe Hart.

“He played a really good game. He made a couple of big saves for us which is what we needed, it helped us stay in it. I think we were actually in that game. But obviously once you go down to 10 and then to nine away from home you’re asking a lot from yourselves.

“But leading up to that there were definitely some positives for us to take. I do feel deep down we were able to walk away feeling that we can compete with these teams if we keep 11 players on the pitch.”

Johnston added: “We play Celtic Park week in, week out and we know what that pressure’s like. We know what it’s like playing in front of 60,000 people who are desperate for you to win and are moaning whenever you pass the ball back. It wasn’t like walking into that stadium and it was overwhelming, which I think really helps us on this stage.

“But, no, I think it’s more down to the fact that these teams are experienced, the fact they don’t feel rushed, they keep playing to their principles while other teams, potentially, when they come up against Celtic sometimes they respect us a little too much.

“Sometimes, as we impose ourselves they wear down. These teams, they try to impose themselves on you. And again, that’s a difficult thing to really play in. But, at the same time, I do think that was a positive step for us. Again, experience does make a difference when it comes down to some of the decisions on the pitch.”

Johnston, who made a vital tackle on Feyenoord striker Yankuba Minteh on the edge of his penalty box when the scoreline was 0-0 in the first half, was struck by the lack of leniency shown by Bosnian referee Irfan Peljto and is confident Celtic will be far warier of committing fouls in future.

“The first red card felt a bit harsh in the moment,” he said. “But Gus was already on a yellow. I think they perhaps give out yellows a little bit easier in the Champions League. They want to make it more of a beautiful game than we have in Scotland. But it’s another learning curve for us.”

It is fair to say that Celtic were, despite back-to-back cinch Premiership wins over Rangers and Dundee and three consecutive clean sheets, not in an especially good moment going into their first match with Feyenoord since the European Cup final way back in 1970.

Cameron Carter-Vickers, their best performer as they won a world record eighth domestic treble last term, and his fellow centre-backs Maik Nawrocki, Nat Phillips and Stephen Welsh are all sidelined by injury and manager Brendan Rodgers had to put his faith in Lagerbielke and Liam Scales. Liel Abada is also out.

Elsewhere, Johnston and Reo Hatate have just returned from long-term injury lay-offs while new signings Paulo Bernardo, Holm and Luis Palma are all still settling in to their new surroundings.

The full-back, though, is hopeful they will improve going forward and can give their next opponents Lazio, who drew 1-1 with Atletico Madrid in Rome on Tuesday night when their keeper Ivan Provedel scored an equaliser in the fifth minute of injury time, a torrid night in the East End of Glasgow next month.

“It is a bit frustrating to lose that record (Johnston had won 20 and drawn three of the 23 games he had been involved in before Tuesday night),” he said. “But it was going to happen at some point. So hopefully we can bounce back and start another streak.”

“I think you can see again what an advantage playing at home is in Europe. That crowd was amazing from the moment we stepped out for the warm ups.

“I’ve only been told, I haven’t seen it yet, what Celtic Park’s like on the big Euro nights. It can be intimidating for teams coming to that place. You’re not just playing against 11 at that point, you’re playing against 60,000 as well. So we’ve got to use that energy to really kind of buoy us to that next level of performance.

“At the same time, I do think when we had 11 men on the pitch, I think we probably had the better chances. Of course, they were at home and dictated the game. But we had the better chances in the first half before that free-kick went in at the end.

“It wasn’t the Celtic you’re used to seeing with free-flowing football and creating chances every couple of minutes. But it still felt like it was one of those ones where you want to be in Europe on the road. You want to be striking distance away. One half chance away from nicking something. So I do think there’s something to take away and we’re excited to play at home, for sure.”