Kieran Tierney is closing in on his Arsenal debut following his move from Celtic

Kieran Tierney announced his return to training with Arsenal by nutmegging Shkodran Mustafi. It was a light-hearted moment to mark the Scotsman's recovery from a hip problem, but his new team-mates will discover pretty quickly that the summer signing from Celtic can cause a stir on the training ground in other ways too. Tierney is full on.

Ronny Deila, the Norwegian coach who gave him his professional debut, recently recalled how senior professionals would give the youngster a wide berth during sessions because of his aggressive approach. Scott Brown, his captain at Celtic, was never one of those but when the notorious midfielder says Tierney would tackle his own granny, it speaks volumes.

Kris Commons was another team-mate who witnessed his development during those first forays into senior football and his memories of Tierney tally with those of Deila and Brown. He acknowledges the talent that saw Arsenal pay £25m for him in the summer, of course. But it was Tierney's passion for the game that really stood out right from the start.

He was like a child who just loved being out on the field doing what he was doing. Kris Commons on Kieran Tierney

"He'd probably have played for free," Commons tells Sky Sports. "He had that mentality. His feet were on the ground. He was never big-headed about being part of the first-team squad, just very enthusiastic. You just had this real feeling about how he played the game. He was like a child who just loved being out on the field doing what he was doing."

Tierney's intensity during training has actually caused more issues for himself than his team-mates. At 22, he has already suffered a number of injuries - and not many of them have been the muscle problems that often affect injury-prone players. Instead, they have been a direct consequence of his characteristically robust approach to the game.

1:50 Unai Emery says that his injured full-backs are close to being fit to play Unai Emery says that his injured full-backs are close to being fit to play

"His enthusiasm has got him into a few pickles, certainly in terms of breaking his leg," says Commons. "There was one training session, he broke it pretty badly indoors on the artificial turf. I was there. He broke his ankle just by going in for a tackle and rolling it. Then I remember a training session in the winter outside and he went in again. It was very similar.

"Even though he had broken his leg before, it didn't faze him. You hear about players who have had long-term injuries and they are a bit apprehensive. They are always a bit nervous when throwing themselves into tackles but it didn't affect him. He just threw himself in and rolled his ankle again. He literally just looked up and said, 'I think I've done it again'."

Tierney and Rob Holding could form part of a new-look Arsenal defence

Tierney approached that injury setback with the same upbeat attitude and was able to return to the team every bit as aggressive as he had been before. "He did the rehab and then he came back with the same energy, enthusiasm and will to win," adds Commons. "It's that never-say-die attitude and it's probably the most important quality to have."

It is, of course, precisely the quality that this Arsenal team is frequently accused of lacking. There was the capitulation at Watford and the wobble against Aston Villa. Tierney cannot address all of the issues alone. The centre-back solution will have to come from elsewhere. But he is a more natural full-back than Sead Kolasinac and that will surely help Unai Emery.

2:57 FREE TO WATCH: Highlights from Arsenal's 3-2 win against Aston Villa FREE TO WATCH: Highlights from Arsenal's 3-2 win against Aston Villa

Although he cannot match Kolasinac for size, he is stronger than he once was. "He is very imposing now," says Commons. "You can see that with his muscle mass on his thighs and his upper body as well." Crucially, he is a more skilled defender too. "I have always thought that the defensive side of his game is the strongest part. I think he reads the game well."

There will be an obligation for Tierney to attack at Arsenal. If Emery opts for a diamond formation then the onus will be on the full-backs to provide the width. But while that may be problematic given the lack of cover currently being provided by the midfield, the prospect of Tierney and Hector Bellerin pushing forward is still an exciting one.

"Whenever I played with Kieran he was always that outlet on the left-hand side who gave the team that natural width because he got forward so well," says Commons. "At times, he was an out-and-out winger for us because we did get our width from the full-backs. He can get across the pitch at pace and in the final third he has good delivery.

"I have no doubt that he will come into the team and make a huge impact. It's his enthusiasm and his professionalism. I think he will bring a lot. Arsenal have had a weakness defensively for a long time. I know what KT can bring and he can go straight into that team."

Tierney's belated Arsenal debut cannot come soon enough.

Follow Tuesday night's Carabao Cup tie Arsenal vs Nottingham Forest with a live blog on the Sky Sports website and Sky Sports App

Highlights of the game will be published shortly after full-time on the Sky Sports website and Sky Sports App