Brendan Rodgers last night warned against "the rot setting in" as he put more pressure on what is an incresingly strained relationship with the Parkhead board.

The Celtic manager also gave the biggest indication yet that if his ambitions are not matched that he would consider his future at the club.

Irked at the manner in which John McGinn was allowed to slip through the net after being courted by the Parkhead side throughout the summer, Rodgers was unambiguous with his feelings at the lack of quality signings made in the transfer window.

Celtic have added striker Odsonne Edouard for a club record transfer fee of £9m as well as backup goalkeeper Scott Bain.

Rodgers has made no secret that he wished to supplement that with other additions and he has maintained that if he is not in a position to do so then there is a danger that he will consider his position at the club.

Asked directly if the day he stops pushing for that quality is the day he wouldn't be there, Rodgers said: “Yeah. My job is done then. Terminado. Gone.

“But that’s the challenge. You have to test yourself to the limit. You have to be couragous as a club.

“It’s a joy to work here. I love my life here and enjoy being the manager here.

“But it’s no good if I just sit back and get comfortable. Being comfortable is the enemy of progress

disappear, and that’s the greatest institutions.

“You have to be mindful of that and keep getting stronger and stronger.

“Dermot [Desmond], Peter[Lawwell] and Ian [Bankier] all want what is best for Celtic. Critically, they are major shareholders and run the club. I have to respect that, and I do.

“My ambition is for Celtic. Every manger is ambitious but for me it’s inherently about the club. We’ve done a double treble, been invincible in one of those seasons, set a British record for unbeaten games.

“We don’t want to stand still. How do we improve? We improve in Europe and in order to do that, it’s simple, is quality players.

“The minute I start thinking otherwise and get comfortable, then progress stops. In football you can’t afford to do that.

“It’s too late once the rot sets in. It’s too late. I’ve always tried to guard against it.”

Rodgers’ comments did not go down well with the Celtic board earlier this week.

The Celtic manager declined to give an answer when questioned as to whether he felt he had been backed by the the Parkhead board.

And Rodgers was reluctant to accept that the public manner of his criticism was responsible for any disharmony at the club.

“It’s not an issue. I haven’t spoken to anyone,” he said.

“I get on with my work. I have good relations with the people here and there’s no issue.

“I’m very happy up here and day-in, day-out, I get on with my work.

“My ambition is always for Celtic, I want Celtic to be the very best.

“I have a huge respect for the board here. Absolutely. They have run the club strategically very, very well. Me coming into here and what I have seen in the last couple of years, I have real good relations with every one of them. There is not an issue there at all.

“My focus is on doing the best for Celtic. Deep down I am a supporter but I am also a professional manager. I also look for the help that is needed to take the team to the next level if that is what the demand is. I will always push for that.”

And while Rodgers accepts that from the board’s perspective spending significant money – in Scottish terms – may not guarantee a further return in Europe, he believes it is imperative to strive for it.

“What we need in the squad in terms of real genuine quality positioning will obviously cost you money,” he said. “It doesn’t guarantee anything. What you would hope is that it would give you a greater opportunity. It doesn’t really change.

“ The game is about quality and quality players. We have some outstanding players here in terms of quality and talents. We are trying to grow and cultivate your squad to the best that it can be and for that you can’t stand still. You have to keep looking to develop and improve it even if you think you are doing ok. That is something that is a constant.