Gordon Strachan: Presence of Celtic defender Kieran Tierney increases Scotland's chances against England

However, the 19-year-old left back, who was switched to the right side of the defence in the national team’s last Group F match against Slovenia back in March, is set to feature this weekend after having a gum shield made for him.

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Strachan, whose side needs to defeat the “Auld Enemy” to boost their slim chances of reaching the World Cup finals next summer, feels the presence of a player whose performances at club level have attracted the attention of several Premier League outfits will increase their chances of success.

“He makes us stronger,” he said following a training session at Mar Hall yesterday. “He saw a specialist this morning and will get a gum shield. He is getting it made at the moment and will wear it in training tomorrow. He did the start of the training and we kept him out of any contact. Then he went away and did his own thing.

“He will be involved in contact tomorrow. The guy told him that once the gum shield is in he is fine. The work that was done immediately has meant he is alright. A specialist at the game took him away and looked after him. He doesn’t look as if he’s in any pain. He is jogging about and laughing and joking with the rest of them.

“It’s not common what happened to him. I have seen incidents occur where players ended up with missing teeth, but this was quite tricky. It was good the surgeon was right there to look after him right away. But Brendan texted me the next again day to say all of the Celtic boys will be fine.

“I would imagine that once this game is out of the way he will have plenty of time to recover. But being the way I am I am kind of selfishly only thinking about this game. I am not thinking about anything else “

Leigh Griffiths, who started up front in the 1-0 win over Slovenia, was feeling unwell yesterday and sat out training along with Darren Fletcher who played in the Michael Carrick Testimonial Match at Old Trafford on Sunday.

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Strachan, though, confirmed that Griffiths will be fine for the meeting with Gareth Southgate’s team on Saturday. “Griff is not at his best,” he said. “He is feeling a wee bit under the weather so we just kept him out of the way. He could have trained at a push, but I told him just to stay in his room. He will be back tomorrow. If there had been a game he could have played.”

The build-up to the game against England has already been marked by some derogatory remarks about Strachan’s side and their players; Graeme Souness has rated them as the worst Scotland team he has ever seen while Paul Scholes has claimed captain Scott Brown wouldn’t get a game in the top flight down south. Strachan said“It’s all opinions. My opinions don’t count. It’s only actions with my team that counts. I have to do things and so do my players. Some of us talk and some of us have to do things. I have to do things and so do my players.”

Asked about the Scholes remarks, he said: “If I was still the manager of any of the teams I had that did reasonably well in the Premier League, I'd take him (Brown).

"Okay, the game might have changed since I was at Southampton. We were fourth in the league at one point and I'd still have had him in the team. But I have no problem with people having an opinion on players.

"But let me tell you, I watched him again in training today and he's back running to how he did when I first signed him for Celtic. That's where he is, and when you're going into big games like this one there's nothing better than having people like him around you.

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"The real test of a player, also, isn't anybody's opinion who doesn't watch him every week. You're big test as a player is what your team mates think of you. When you finish your career that's what matters. The rest don't matter, your team mates are the only ones who are the test of who you are, what you are and what you brought to a team."

Strachan added: “Honestly, I don't think the man sleeps, but if he did he wouldn't have lost any of it. I don't think it'll have bothered him one little bit.

"It's like the Player of Year awards. People were asking if he would have been upset (at not being nominated). I think he would have been delighted. It meant he didn't need to sit in front of the media and talk, or get dressed up for a ball."

The game against England on Saturday will come a full month after the players who ply their trades in Championship down south – including expected starters Russell Martin and Charlie Mulgrew as well as Ikechi Anya, Christ Martin and Steven Naismith - last played in a competitive fixture.

But Strachan has no concerns about the match fitness and sharpness of his players following their first training session yesterday. “The players didn’t show any signs of tiredness,” he said. “The training was inspirational today.

“There is a group of them that’s gone about a month without having a game so we had to put on extra stuff for them this morning, hard work, after it was finished.

“We took them away and the rest of the lads went ‘well if they’re doing it, we’re doing it’. So they all joined in. Much to the concern of the fitness coach, who was having kittens at the time!

“I thought ‘I love this, this is the way it used to be, that the top players set the standards of fitness and where you want to go’. So they set the standard today for how they want to go about the game on Saturday.

“The top players said ‘we’ll join in’ so everybody joined in the hard running, which they weren’t meant to do. The fitness coach was having kittens, but I’ve been saying to the fitness coach for years that the top players determine how far they push each other.”