“See, just me saying this, I can see my mates saying: ‘You’ve changed, man.’” Kieran Tierney starts laughing. He knows but he can’t help it and if they were where he is, they wouldn’t either, he’s sure of that. The defender is talking txuleton, the Basque T‑bone. “I’m not big on taking pictures of food but every time I get one of those, I do: it’s different class. And there’s a dish that’s rice and clams,” he says, which is when he checks himself and cracks up, imagining pals back in Scotland shaking their heads. “Rice with clams?! You never got that growing up. But it tastes unbelievable, man.”

Things are going well in Spain, then? “I love every part of it,” Tierney says. Well, maybe not every part: there have been two hamstring tears, first against Athletic Club in late September then against Celta Vigo at the end of January, the latter forcing him out of Wednesday night’s Champions League trip to play Paris Saint‑Germain. But every other part of the Arsenal full- back’s move to Real Sociedad has been good and, though this hurts, even injury can have positives. That’s how he approached the initial setback, at least: “I used the time to learn the gameplan inside out and learn more of the language,” he says.

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The food in the city is just one of the “many bonuses of San Sebastián”, Tierney says. “The place is beautiful: the mountains, the scenery, the sea. The people are the friendliest people, so helpful.” And the football’s not bad either. He has played 16 games and although la Real have slipped to seventh, they won their Champions League group without trailing for a minute, despite this being their first appearance in a decade. They also have a Copa del Rey semi-final to come. The style suits too, back to what he knows.

“We talked about the style of play,” Tierney recalls. “That was the main part for me because at Arsenal it was slightly different. I wanted to know how they see their left-backs. And when they told me, I was delighted.

“One of the big things about Arsenal is their left-back is one of the most central players; [Oleksandr] Zinchenko is one of their biggest creators, more like a No 6. When that first got introduced, it was alien to me. I had never played as centre‑mid, even as a kid. I was always high and wide, what you would call the more normal left-back position I’d kind of known all my life.

“I was trying to learn that [new role] at Arsenal. You see how well it works and it’s hard to question: I tried my best, learned, tried to do it in training and games. Maybe I can be very comfortable in that position one day. I got to practise with one of the best in the world, Zinchenko. It’s so natural to him, he makes it look so easy. But for me it’s probably more natural now, going up and down the wings.

“When I first came, the coaches showed me videos of left-back movements from last season. Aihen Muñoz [the other left-back] was amazing, one of those who’s helped most. In training he’d say: ‘You need to do this, do that, pass here.’ At first, you’re asking the rules: ‘How many touches, how many passes?’ But now it’s: ‘That’s that drill, that’s this drill.’ I’m asking less questions. You can still play well but it takes a little while to adapt. For others, it was second nature.”

There is a reason for that. Eighteen academy players have played for the first team this season; 13 are from Gipuzkoa, the province of which San Sebastián is the capital. The smallest in Spain, it is also home to Mikel Arteta, Unai Emery, Xabi Alonso, Andoni Iraola, Julen Lopetegui and Real Sociedad’s coach, Imanol Alguacil. “Honestly, it’s just crazy,” Tierney says. “Look at the managers from the Basque country, the players. It’s some doing, honestly. It must be the culture, how they’re brought up, the way they think about football.

“These boys are like me playing for Celtic. Growing up, the club is all you know and all you want. When I was at Celtic, there were four or five maybe in the first team from the academy. Here it’s like 13, 14. Next level. The squad are really tight. I noticed that straight away. You could tell they had been playing together for years, the manager has been here for years. It doesn’t matter if you’re playing, on the bench, not in the squad, you all want the same. That’s part of the success: it’s a family.”

A talented one, too. “I was up against Take Kubo in the first couple of weeks training, so to see how sharp he is struck me. You have world-class players like [Martín] Zubimendi, [Mikel] Merino, Brais [Méndez]. It’s not that people don’t think they’re good; it’s just that if you’re only watching the Premier League every week, it’s hard to know. They’re world class, and for so many to come from the academy is incredible.”

***

“I think most will look at this game and say PSG are favourites,” Tierney says, which is not to say he agrees. “It’s maybe the toughest draw. They have been in this competition years, they have the experience, world- class players.”

He knows: he has faced them before. Back in 2017, Celtic played PSG twice and lost 5-0 and 7-1, thanks for the reminder. “Erm … it was hard,” Tierney says. “I was up against [Kylian] Mbappé; and he’s scored, what, 200 goals since? It was him, Neymar, [Edinson] Cavani.”

There’s a pause, a grin. “So that was quite a good front three, anyway. And the year before we got Barcelona. We didn’t get any luck with the draws at Celtic. But it’s all experiences, it adds to what you are. I was 19, 20 against PSG; it can happen. You go through big defeats and it helps you in the long run.”

He is 26 now and there was guidance along the way from Brendan Rodgers and Emery, men who haven’t always had the credit they deserve. “Brendan was massive for me,” Tierney says. “Ask anyone at Celtic: he made winning a treble normal, which is the craziest thing. He transformed the club and my career. And I loved working with Unai Emery. Unfortunately, us players never got the results he deserved. I don’t think it’s on him. He worked so hard, every single day he gave us everything, and ultimately we never got the results.”

Why not? “If I knew that, I would have a job higher up in football. Often in football, things don’t go to plan. It was sad, but you see what he went on to do in Spain and now with Aston Villa.”

And so to PSG, first away and then at the Reale Arena in a fortnight. “I do find it hard to watch games when you’re injured,” Tierney says. “I love supporting the team at the ground but on television you just think: ‘I wish I was there with the boys.’ We know it will be really, really tough but these are the games you want. Being here, topping the group is an unbelievable achievement, an amazing story. We only conceded two goals, we won the group deservedly. We went away to San Siro and handled it so well. When you get a tie like this, you don’t fear it; you enjoy it, embrace it.”

Just like he has. “I love it here, I’ve been so lucky.” Flights aren’t so easy – although he’s checked and there’s an Edinburgh-Biarritz route opening in April – but his family have been out. And what do they say? Can you stay?, probably. He laughs. “‘How long’s the loan?!’ Yeah.”

Actually, that’s a good question. What does happen when this season ends? “It’s hard to say anything,” Tierney replies. “But I love it here. I loved my time at Arsenal too and I still have two years on my contract, so if I’m back there …”

Win-win? “One hundred per cent. Arsenal are amazing. They’ve helped me the last four years. Even this season, letting me come here and try this, experience it. They had [Jakub] Kiwior’s injury and it would have been easy to say: ‘No, we’re going to stop it.’ But they were open, honest and said: ‘On you go for a year.’ I’m very grateful. I don’t know what’s going to happen but I’m loving it, I’ve adapted well. I’m older now so it was 10 times easier than leaving home for London. There’s still time to go, so I hope I can play well and return the faith everyone here has shown in me.”