The improvement in Stuart Armstrong last season was rightly highlighted given the stark spike in the quality of his performances for Celtic under Brendan Rodgers.

Then, his impact when he was brought into the Scotland side was clear as he orchestrated the crucial win over Slovenia in earning his first cap, which manager Gordon Strachan hailed as one of the best debuts he had seen.

Callum McGregor meanwhile, has quietly been forging his own path to improvement under the tutelage of Rodgers, and until recently, had been a little lost in the media glare surrounding his teammate.

Not any more though. The midfielder’s double against Hibs on Saturday was just the latest example of his emergence as an operator of genuine quality.

And with Armstrong out of his country’s critical qualifier against Slovakia this Thursday, the creative burden from the centre of the park may well fall on McGregor’s shoulders.

Billy Stark, who knows the player well from his days in charge of the Scotland under-19s and under-21s, believes that McGregor has already emulated his teammate in terms of his dedication to his improvement as a player, and he hasn’t put it past him replicating the sort of debut that Armstrong produced in the dark blue this week.

“I knew right away when Brendan Rodgers came in to Celtic that Callum would be his type of player,” Stark said. “I have to admit, I didn’t think he would get him to the type of level that he is at now.

“He doesn’t give the ball away, he’s not negative in any way, shape or form, and I think it tells you everything about his all-round game that he can fit into so many different positions.

“He can be a real creative force in terms of providing and finishing, and you don’t underestimate the value of players like that.

“Stuart and Callum have had different backgrounds in football. When Callum was a young boy I remember going down to watch him when he was on-loan to Notts County.

“I had him at under-19s and with the under-21s, and he was a joy to work with. That’s another thing that comes into it as well. It might be down the list of priorities when selecting a squad, because if you’ve got a fantastic player who wins you games but he’s got a bad attitude around the place, then you can make allowances as long as it’s not affecting the other players. But when you have somebody who is receptive to what you ask them to do, that is a real bonus.

“Callum has got that, he wants to improve. He wasn’t scared to go out on loan to a lower division English team, and he played well for them.

“He came back to Celtic and wasn’t able to really make that breakthrough straight away, but he’s now showing his ability and he will be one of those 16 or so players who will be the backbone of any success Celtic have this year.

“Stuart made an impact on the first-team at Dundee United and got his move to Celtic, but then had to come to terms with being a Celtic first-team player and maybe not playing in the position that was best for him.

“Callum’s development probably doesn’t seem as drastic as Stuart’s, but I think that it has been. People always knew his ability, but he’s grown to be a real factor in the game. He’s not the biggest or the strongest, but he is overcoming that by being busy, always wanting to get on the ball and being brave on the ball.

“He doesn’t make safe passes when he doesn’t need to, his first thought is to penetrate, and Brendan has been able to give him the confidence to put all that together.”

While recognising that McGregor could have made an impact on the Scotland side before now, Stark is one of the few people in Scotland it seems who could understand Gordon Strachan’s perspective and reasoning behind leaving him out until now.

“Everybody can make a case for a particular player when you’re doing well, and the international squad can’t contain 90 players,” he said.

“There are a lot of things to consider as an international manager. Loyalty comes into it, what game-time they are getting. Then when they do come in, how do they train?

“In terms of Callum, I don’t think anyone could dispute that he’s a lovely footballer to watch, it’s just about those other things that come into it. Gordon has always stayed loyal to certain players, and I can understand that having been there.”

Stark, of course, knows only too well what it must have been like to have been in McGregor’s shoes of late too, having also been forced to watch his teammates disappear on international duty throughout his career.

He surely must be one of the most talented Scots to have never turned out for the national side, although the modest Stark only grudgingly admits that he might fancy his chances if he was playing these days.

“International selection was never something that ate way at me, I was happy to be playing at the level I was playing,” he said.

“I don’t want to sound as if I wasn’t ambitious, because everybody desperately wants to play for their country, but every time a squad came out I didn’t think ‘I should have been in there’.

“I was competing against the likes of Gordon himself, Graeme Souness, Asa Hartford, Archie Gemmill, Jim Bett and Paul McStay, so I recognised how good those players were and that maybe helped me.

“John Wark was also there, who was a similar type of player to me in terms of a midfielder who scored goals, so he had that covered.

“You always become a better player when you stop playing, and judging eras is difficult as well, but I think most people would concede that the quality of player we had when I was playing was better than we have now.

“If I was playing nowadays to the same level, I might feel a wee bit differently, and would feel I had a good chance of being in an international squad, but in those days, I knew I was up against real quality.

“I would liked to have had that honour, but it wasn’t to be. It’s just one of those things.”