GORDON Strachan continues to throw his weight behind the Celticisation of his Scotland squad. Six players from the Scottish champions started in the narrow victory over Slovenia in March and it would not be a huge surprise were all to also feature against England at Hampden in a fortnight’s time. Given their form, both individually and as a unit, it is difficult to make any kind of case against that, the only surprise being that Callum McGregor was not also asked to join them.

Brendan Rodgers has drawn so much more out of previously under-performing players since succeeding Ronny Deila as manager but perhaps one of things often overlooked is how much fitter they appear. It is not a coincidence that no domestic side found a way to pound Celtic into eventual submission, simply because at no point did they ever seem to be suffering from tired legs. And this having played 59 matches this season, far more than any of their domestic competitors.

Instead, it has been the opposition who have tended to suffer, Celtic’s superior fitness allowing them to bombard teams with attack after attack, picking a way through locked defences either by stealth or strength. It has made a substantial difference to some like Stuart Armstrong who has graduated from being not in the squad to a certain Scotland starter.

It will take more than six Celtic players with reduced body fat to knock over England at Hampden on June 10 but Strachan believes it is a positive starting point.

“Have I noticed a difference in the Celtic players’ fitness? Absolutely, yes,” the Scotland manager said. “If you ask me that question then I have to say that. It is very hard on Ronny and his background staff that went before but that is fact. We have seen it in front of our very eyes. As I say, fitness allows you to do things like pressing and keeping the ball.

“What Stuart does - the way he beats people - that is all down to his fitness. He has always had that technique, it is adding that extra all-round fitness that makes you a better player. It is Juergen Klopp’s mantra, Mauricio Pochettino’s too.

“You have to be fit. Pochettino got rid of the older guys [at Tottenham Hotspur] who would maybe stand around, and look at them now. They run all over place. He wanted them angry.

“Unfortunately as an international manager I can’t work on their fitness. You can’t get them any fitter in two days, it doesn’t work. In fact if you try to push them it can be a negative. Before you know it they have strained something.”

Armstrong has benefited more than most from Rodgers’ dedication. Barring injury he is now a nailed-on certainty to start against England on June 10 following his impressive debut against Slovenia.

“I would say when we were naming squads in September there wasn’t a clamour for him,” Strachan said. “People weren’t asking ‘Why’s he not in?’ But since then he’s been terrific. He’s always had that fitness, but he’s now taken it to another level. He’s no longer leaving footprints, he just flies about the pitch. His overall performance on his international debut was terrific. His fitness in the last five minutes allowed him to beat two people and put a pass in.

“I’ve seen it many a time of players in that position, they lose the ball because they’re tired or the final pass goes astray and people think ‘unlucky.’ But it’s not unlucky, it was just because the player wasn’t fit enough.

“I say it to players all the time, that physical fitness helps you with the mental strength - and Stuart knows that now. He runs players in his area to a stand-still. It’s a real negative if you’re playing against him - you’re left thinking ‘I’m not as fit as this fella’.”

Just as players from one club side will dominated the Scotland team, so it will likely be with England, with five Spurs players named in Gareth Southgate’s squad. Dele Alli, in particular, is someone who has caught Strachan’s eye.

“He is the perfect number 10,” he said. “You have to have the ability to run beyond the striker, and he’s perfect for that now. He can play between the lines and if you’re pushing up he’ll run in behind you. He gives you all sorts of problems.”

Strachan’s assistant, Mark McGhee, is a fan, too. “I was at the Spurs versus Bournemouth game a few weeks ago and saw Dele Alli and the others,” he said. “He's getting away with murder at the moment with referees as he's the golden boy. He was kicking the ball away and the ref was having a laugh with him!

“But my God he's a good player. That Tottenham team that day were terrific, with all of the boys who'll play against us, Alli, Harry Kane, Eric Dier, and Kyle Walker. They're a very good team. And they could have six players in the England team to face us, which is similar to us with Celtic.

“I don't think that's a bad thing because the others who'll make up the team are top players as well. The Spurs boys have an understanding which should help the spine of the England team. I hadn't seen Kane enough to really appreciate him before. But I'm starting to get what all the fuss is about now. He does a lot of things that are difficult but made them look easy. He's also stronger than I thought he was against centre-backs. He's a really good player as well.”