BRENDAN Rodgers has attributed the loss of confidence experienced by Stuart Armstrong to his failure to agree a lucrative contract extension with Celtic and suggested the midfielder has been poorly advised by his representatives.

Armstrong was one of the outstanding performers in Rodgers’s team last season as they qualified for the Champions League group stages, won a Betfred Cup, Ladbrokes Premiership and William Hill Scottish Cup treble and went undefeated domestically.

However, the 25-year-old, who was awarded his first Scotland cap against Slovenia in March as a consequence of his fine displays for the Glasgow club, has been unable to replicate that form so far in the 2017/18 campaign.

The inability of the former Dundee United man, who struggled to establish himself at Celtic before Rodgers arrived last year, to reach the same levels as he had previously scaled has concerned his manager.

Having Armstrong at the top of his game would certainly be a huge assistance to Celtic in the Champions League play-off games against Astana of Kazakhstan in the coming days.

Rodgers, who voiced his concerns about the player’s state of mind following the Premiership match against Partick Thistle at Firhill on Friday night, stressed he would be in his squad for the first leg at Celtic Park this evening.

But the former Swansea City and Liverpool boss believes Armstrong, who has been linked with a move to Barclays Premier League club Southampton, has been adversely affected by the ongoing impasse over his future.

The Northern Irishman stated the stand-off is impeding his continuing development and should have been sorted out “a long time ago”.

“I have regular chats with Stuart," he said. "He is someone that I really respect as a person and I really respect the development that he made as a player last season. I want him to get back to that level.

“He’s a thinker. He’s a clever guy. What worried me the other day was that I saw something in a player that I hadn’t seen from back when I first came in. That is where the contract situation comes in. It is about finding that stability.

“There has been an offer there for a long time now which is a really, really good offer. But if representatives feel there are maybe other options for him - and we haven’t had an offer – and they want to wait and wait and wait and wait to see what happens then, okay, that’s what you do. But the player suffers.

“It’s not the boy, it’s not him. If you’re paying someone to make decisions for you and who’ll gain their commission from it then of course that’s what you look towards. Listen, most players have representatives. They are there to represent them.

“But it is something that could and should have been done a long time ago. That’s my feeling on it. But I have a feeling it might go to the very end of the transfer window.

“In Stuart’s situation I would love for him to have it resolved, but unfortunately it doesn’t look as if that will be in the immediate future. There will be reasons why which his representatives will have. I have got an idea of the reasons why.”

Asked if the contract offer could ultimately be taken off the table, Rodgers said: “I wouldn’t want to at this stage. I don’t see how that works really. Plus, I wouldn’t want to do that to Stuart. He is a young player, he is a good fella, I want to help him. I want to develop him. I still believe this is the best place for him to be.

“With all due respect, probably outside of Scotland nobody knew of him six months ago. That’s the reality of it. Over the course of the season he developed into a very good player. I still think this is the best place for him to develop.

Asked what he had noticed in his play against Partick, he said: “Just a lack of confidence, nothing behaviourally. It’s just when you see someone’s confidence being effected. When you see a sort of nervousness when he made a pass.

“I’ve known him long enough now. I saw what he was when I came in and I watched him grow and develop. Then I see where he is now. And I don’t want him to be there. I want him to be the best player he can be.

“But I can reassure the supporters that, for me, this is a player who does want to be here. He genuinely does. I sense that from him, from good conversations which are very open. I feel that. It’s not the case of him not wanting to be here. I don’t believe that.

“I just think it’s something that’s dragged on way, way too long for what, with all due respect is a simple deal. This is a simple deal, not a big multi multi-million pound deal.

“This is a simple deal that should have been sorted out before the end of last season. Now it’s dragged on and on and on.”

Rodgers fears it will be difficult for Armstrong, who is under contract until the end of this season, to get back to the level that he was at last term until the situation is resolved.

“There are certain characteristics with players who can deal with it,” he said. “Some players can do it, I’ve had players before like that. I had (Luis) Suarez who got through it. It’s just the mechanics of the different type of person.

“But that’s something you have to do. No matter what’s going in with the background noise, your money is in your bank every month and every day you’ve got to perform.

“And if not then it’s very simple. I don’t pick the team, the players pick the team. I can mould then and construct them to work a certain way, but that’s how the game goes.

“Listen, Stuart is fine. He’ll be in the squad and he’s a player I’ve really enjoyed working with. That’s one of the frustrations of this, for me, because it’s such a simple deal. Six months ago it should have been organised, sorted and done.

“And how modern football works, if a club wants you from the Premier League they’ll pay for you. Goodness knows, they’ll pay for you. If you’re a player up here in Scotland you don’t need to worry about signing a new deal thinking it’s going to hold you back.

“The game has changed. It doesn’t work like that. You can gain yourself six months’ money and still go if that’s what you want to do.”