It wasn’t so long ago that Kieran Tierney’s teachers raised a tired eyebrow and told the youngster to knuckle down to a real job.

Telling them that he planned on playing football for a living carried little truck as they told the then aspiring full-back to focus on life on the 9-5 beat.

His motivation, however, was never on proving them wrong but rather on proving himself right.

“I remember when I was at school and I was picking my subjects we had to put down what we wanted to do as a job,” said the 19-year-old. “I always picked football.

“But the teachers told me I can’t do that and I should write down ‘joiner’ or something like that.

“I always chose football though. I’d been playing for Celtic for six years by that point and someone was saying I couldn’t play football!

“I wasn’t out to prove anyone wrong, it’s just what I wanted to do.

“My mum, Gail, is actually a dinner lady at the school, Our Lady’s in Motherwell, so she always gets asked how I’m doing and I’ve been back doing awards ceremonies and stuff. It’s been good.”

Tierney came firmly into prominence last season under Ronny Deila but he has maintained his place under Brendan Rodgers.

At one of the first press conferences with the former Liverpool manager, Tierney’s name was singled out as one of those at the club that he felt could go on to play at the very top level.

The manner of Tierney’s performances at European level would give credence to that theory but part of the reason why he has made such a strong impression on the first-team is his attitude.

Level-headed and keen to take on board the advice that has been dispensed towards him, the teenager hasn’t been carried away with the early trappings of his position.

Indeed, he still stays at home with his folks and while his dug money might have gone up a bit in the last 18 months, he has credited his parents and friends for keeping his feet on the ground.

“My family keep saying they can’t believe it,” smiled Tierney. “It’s mad really. Everyone dreams of this but you never really expect it.

“Everyone is happy and proud. It’s good for me and it makes me happy to make my family proud.

“I try to do the same things. A few people want pictures and stuff, but apart from that it’s just normal for me. I still live at home with my mum and dad.

“It’s just the easiest thing for me. It saves me cooking and doing the washing and ironing!

“My mum has been great. She’s never on to me to tidy my room, so it’s ideal really.

“To be fair my dig money has gone slightly up, but I don’t mind that. It takes a wee bit of pressure off them.”

It is on the park, though, where the teenager has made his mark.

Calm with ball, aggressive in the tackle and an aptitude for getting forward, Tierney is capable of fulfilling the demands of the modern fullback, even if there is something of the throwback in his unfashionable black boots and socks at his ankles.

The Champions League playground was always going to provide a few tests, though, and coming up against Lionel Messi and Raheem Sterling has not been without their challenges.

“He [Sterling] is one of the world’s best wingers and one of the fastest guys in football,” he said. “So it was a great experience for me to play against him.

“I felt I did okay. He is a £50 million player, so he is going to get crosses in and do good stuff in the game. You expect that. But I tried my best against him and hopefully did okay.”

Tierney’s shot was deflected into the net by Sterling for Celtic’s second goal on Wednesday night, a game that marked Tierney’s 50th appearance for the club.

UEFA were a little harsh in awarding the strike as an own-goal, but Tierney was insistent on claiming it.

“It was a great through ball from Tom [Rogic] and luckily it has ended up in the back of the net. Me and everyone else inside Celtic Park celebrated like it was mine, so I’ll take that.

“I didn’t notice the name of the scorer changing on the scoreboard, but someone told me afterwards. As long as it went in, I wasn’t really caring.

“But I won’t correct anyone who congratulates me on scoring it! I just tried to hit it towards the back post and make sure it beat the goalkeeper. Sterling deflected it and it went in.”