CELTIC look to be playing a dangerous game not only when it comes to qualification for the Champions League group stages this season, but also when it comes to keeping their manager happy.

Grumbles from supporters over the lack of summer signings aren’t anything new at Celtic Park, and given the importance of Champions League football to the club, I have to agree that it is a little surprising the Celtic board would play it so fast and loose when it comes to giving themselves the best possible chance of making it to the promised land. But this is the first time that I have seen and heard the manager being so obviously annoyed about their lack of activity in the transfer window.

Losing out on John McGinn was undoubtedly a blow for the club, and it clearly irked Rodgers that the club had allowed him to get away over their reluctance to put up the necessary cash until Aston Villa brought their bid to the table. But I would argue that if Celtic do indeed miss out on Champions League football this season – and after their home draw with AEK Athens, that looks entirely possible – it will be a lack of investment at the back that will have cost them dear.

What I don’t understand is the reluctance to put up the necessary cash to strengthen in that area. Celtic must have known that it was a possibility Dedryck Boyata would be unavailable for even this stage given the strength of the Belgian side at the World Cup, and with Jozo Simunovic off the boil, they were left light at the heart of the backline.

I don’t want to be too harsh on Jack Hendry and Kristoffer Ajer, who are still relatively young players who have a lot of development ahead of them, but going into the game against a side of the calibre of AEK Athens with two centre-halves who were playing for Dundee and Kilmarnock not so long ago was always a risk, and so it proved on Wednesday night.

It’s not as if they are short of money. The two years of Champions League football that Rodgers has delivered has left the balance sheet in a healthy state, so it doesn’t make sense to me for Celtic to wait until after they have qualified, or not as the case may be, to address the issues that their manager has raised.

Celtic may have dominated Scottish football for the last couple of seasons and won every trophy going, but they have to keep moving. You can’t stand still. You have to evolve a squad not only to keep things fresh, but to keep the players who are already there on their toes.

Even outwith their issues at the back, if you think way back at the start of pre-season, Rodgers was making the point publicly about the players they had lost like Stuart Armstrong and Patrick Roberts. And yet, here we are now with Celtic staring at a potential exit from the Champions League and nothing has been done apart from bringing in Odsonne Edouard. Yes, they broke their transfer record to do that, but given they raked in £7m from Armstrong’s sale to Southampton, that would hardly have broken the bank.

These issues should have been addressed way back in June when they were raised. Are Celtic’s board naïve enough to think they are going to cruise through every year? I doubt that Rodgers is, and that’s why there appears to be these first signs of a fractious relationship developing between the manager and the board.

The last two years have been so smooth in terms of the relationship between Rodgers, the club and the fans, and everything in the garden looked so rosy when they took the second treble in a row back in May but, two or three months on, there are some small cracks appearing for the very first time.

Do I think that Rodgers would consider walking away if they fail to make the Champions League, and he holds the club responsible for their reluctance to support him in the transfer market? No, but Celtic have to be really careful that they don’t risk losing a man who is there to deliver 10-in-a-row in the long-run.

They have got to keep him happy. When you have a top manager like that, you have to make sure he is fulfilled, and for me, the club should be bending over backwards to give him whatever he wants.

Celtic are never going to go outwith their means, but they are a club with money, and if realistic targets have been identified, then just go and get them. What is the stumbling block? I just don’t understand why you would risk upsetting a manager who has delivered back-to-back trebles over the sake of saving a relatively small amount of money.

The McGinn pursuit was the perfect example of this, but Celtic’s loss is Aston Villa’s gain. He seems to have taken everything in his stride throughout his career, he is so level-headed and such an honest player that I can see the Villa fans absolutely loving him.

The chances are that he will play more football there than he would have at Celtic, which is good for his Scotland career, but there is no doubt that he could have been a big player for the Scottish champions given the opportunity.