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 sparking form so far in the 2017/18 campaign.

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, who has brought in Olivier Ntcham from Manchester City for £4.5 million this summer, 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,” said Rodgers. “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, OK, 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.

“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.”

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.”

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. I just think it’s something that’s dragged on way, way too long for what, with all due respect is a simple deal.

“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 because it’s such a simple deal. Six months ago it should have been organised, sorted and done.”