Ronny Deila has glimpsed the potential of James Forrest over the last month – but believes that the winger is only playing at 50% of the level to which he is capable of.

The Scotland internationalist has slowly hinted that he is close to returning to the level which won him the PFA Young Player of the Year award in 2012.

Deila effectively closed Forrest down for an entire season last year after the 24-year-old repeatedly broke down with a succession of different injury issues.

The Celtic manager believes that such was the manner in which he was laid low by the problems that he could even have been lost to football entirely.

“Yes, of course,” said Deila when asked if that was a distinct possibility. “The work that the medical staff have done has been fantastic and so important. One year ago he was not a happy football player. Everyone talks about potential but how many times have we seen it? On Thursday you seen a player who worked hard defensively and who caused them problems defensively.

“It is a lot of talking about results here and I really understand that, it is no problem. But as a coach you have to see behind it and what is actually happening now is that you can see a James Forrest. “When have you seen him like that? I haven’t seen him even near to what he is now. I said to you earlier that he needs time because he was so long down injury wise and it takes time to get back again.

“Now he has been injury free for eight months.

“Before, in the games he played he was giving me heartache because we didn’t see the intensity we needed to see but I know because he was not fit enough it wasn’t there and also he was afraid to get injuries.

“He had to get over that boundary to understand that nothing was going to happen and he could give 100%. The development he has had over the last month has been tremendous. When he gets 100% in training and in matches then we have a top, top player and he can do it at that international level.”

It was Forrest who set up the second goal during the 2-2 draw against Fenerbahce on Thursday night while his conviction and attacking flair were reminiscent of the player when he first broke into the Celtic team.

"He has balance, speed, technique at the highest level I've seen," said Deila.

"If you get the other things right and can count on him defensively and offensively, then you have a very good player.

"If he continues his development, I’m sure he will be a very important player."

Meanwhile, Deila has also urged his players to retain their domestic focus ahead of Sunday's game at Hamilton against Accies.

"It’s a very different environment but it’s a very important game," he said. "We’ve done this a lot of times and done it well.

"We played well after our last game in Europe and that’s what we are aiming to do now as well.

"We’ll be a bit tired after the game on Thursday but we have a big squad and also players who are used to playing games three days after a European match."