The talented 22-year-old has endured a horrendous two-year period with injuries. He lost almost 12 months to a ligament problem that required surgery and, just as he had shown up well in pre-season under new manager Ange Postecoglou in July, suffered a hamstring tear that he has only now recovered from.
A genuine talent, Johnston’s abilities have never been in question. However, his capacity for the rigours of the professional game inevitably come into question through spending so long on the treatment table.
Celtic’s recruitment of a new head of sport science a month ago with the appointment of Anton McElhone could have a crucial role in getting his Celtic career back on track. Johnston is doing everything in his power to move on from a set of debilitating issues and prove wrong the naysayers who he believes put his injury problems down to some deficit in his professionalism.
“I’m feeling good and the new sports scientist has come in and helped me a lot,” the Celtic wide man said. “I’ve needed a bit more time to get myself back up to speed and to make sure I don’t pick up more injuries.
"I’ve been working hard and the international week came at a good time for me. I was able to get a lot of good fitness work in and some strength work that I wouldn’t necessarily get just from training.
“It’s not just the sports scientist, we’ve nutritionists at Lennoxtown. I’ve had to try and live a bit like a monk recently so I’m not getting any muscle injuries. A player like me is going to be a bit more susceptible because I’m a bit quicker. But, he’s helped me a lot.
“It can be difficult due to the amount of spells I’ve had out. Mentally it can take a toll. But I’ve come back and I’ve got confidence from senior players like Joe Hart. They’ve helped me a lot. I’m starting to get a bit more belief in myself again.
“I had the summer off, but I never took it off. I had surgery, I was working right away, in the gym and seeing the physio and doing a lot of fitness work. Obviously, I played two games quickly and my hamstring went. It was a very low time.
"A lot of people don’t know what goes on in the background. They’ll think I’m lazy and not a professional. But I try to do everything to get myself right to play for the club. Thankfully, it’s starting to pay off now and I hope people will see that.
“Being a Celtic fan, if supporters don’t like you it can get to you a bit. But the manager’s the one who picks the team and I’m back and he’s putting me on. He obviously wants to see me out there and that gives me confidence as well. I just wanted to prove people wrong and show that I’m good enough to play for Celtic.”