Speaking to Scottish FA’s official podcast, the Celtic left-back looked back on his rise from precocious youngster to fully-fledged starlet.
The 20-year-old was just 18 when he was handed his maiden call-up and cap by Gordon Strachan, the adjustment made easier with the large assemblage of Celtic players.
“I think I still had my braces on,” he said, “that’s how long ago it was. A few boys, Broonie and the Celtic boys are here which helps you blend in straight away.
“All the other boys are great with you, make you feel welcome and the staff are great at that as well. It’s new but it feels as if you’ve been there a while the first time you go.”
Following Friday evening’s 3-0 victory over Lithuania which keeps the country’s hopes of qualifying for the World Cup in Russia intact, Tierney has amassed five caps in three separate positions, and for the second time fielded at right-back where he put in a strong, confident performance.
Tierney can only remember playing the position once before he started on the right in the 1-0 win over Slovenia at Hampden Park.
He said: “The three competitive games (prior to Lithuania) have been three different positions which is hard for somebody so young. But for me it is good, learning different parts of the game.
“The manager’s been great with me, the coaching staff as well. It’s something I look forward to; I don’t dread coming to play a different position, I do like it and look forward to it.
“It’s hard to adjust but that’s what you need to do as a footballer, you need to try and help the team. I’ll play anywhere if it benefits the team and the manager. So I don’t mind at all.
“I think I played it once, at under-14s or 15s in the Nike Cup but other than that it was all new.”
Yet, left-back was not always Tierney’s position having been fielded further forward as a youth player.
“I played left-mid,” he said. “I didn’t enjoy that as much as I enjoy defence. My dad always said you see the full game in front of you, you can run on. If it’s left-mid I need to play, I will play there.
“For me, in my head, I have always been a left-back since I was young. It was just certain coaches didn’t like me playing there and didn’t think I was a left-back. That’s what you have to deal with and when my time came I put myself at left-back.”