DISASTROUS. Embarrassing. Completely self-inflicted.

That’s how I feel about losing four goals at home to FC Cluj and with Celtic’s not making even the Champions League play-off for a second year in a row.

Being ahead in a tie after the first leg, albeit on goal-difference, Celtic should never lose when the second game is in Glasgow. They were through if they conceded no goals. As it turned out, they could have qualified having given away two.

Celtic were ahead twice in the second half at 2-1 and 3-2. The third goal came with 14 minutes to go. There was enough experience and talent in the team to see out the game.

That Cluj then scored twice is, to me, unacceptable.

I didn’t see this coming. Neither did the supporters. There was no angry reaction at full-time, a few boos aside. A full Celtic Park couldn’t quite believe what they had just see and walked out without much to say.

There isn’t any positive spin. If we had lost to a better team then that’s one thing. We scored four goals over two games against a side who I thought were decent but not better than us, and still we are out.

Neil Lennon’s job now is to make sure this doesn’t demoralise his players. A home game against Dunfermline in the Betfred Cup isn’t the worst way to follow up such a bad evening.

Neil is going to be criticised and he won’t be the only one. He’s big enough to take it and strong enough to take it. I just hope the players are as well because failure to reach the group stage, and they fell well short, could be something they carry with them.

And Rangers will be boosted by Celtic falling to a relatively small team. I’ve said time and again that this season will the first that we get a proper challenge in the league. The gap has closed and Tuesday showed that Celtic are a team that can be got at.

Okay, where to begin.

It is clear that Neil doesn’t fancy, at least right at this moment, either Christopher Jullien nor Boli Bolingoli, the left-back in particular having a poor game in the first leg.

As has been mentioned more than once, there was £10million on the bench and the supporters unsurprisingly want to know why.

I was surprised Neil didn’t look to Johnny Hayes who isn’t a natural left-back but has never let us down.

I’m not saying Callum McGregor can’t play that role but, for me, the midfield triangle of Scott Brown, Ryan Christie and Callum worked so well in the first leg. I wouldn’t have changed it.

I know he wanted Olivier Ntcham to play, and he did well, but Callum is key to everything the team does.

However, we scored three goals at home which should always be enough to win. But the defending was awful. Cluj looked like scoring every time they went up the park.

Indeed, they did score with near enough every attack.

It was silly mistakes, lapses in concentration, which cost us. When Scott Brown has a bad game, including giving away a penalty, you begin to think that it’s not going to be your night.

The supporters might not have said too much on Tuesday but they have been loud since then. The anger will take some time to subside.

It’s not to much the money the club have missed out on, it’s the prestige of playing in the Champions League against the best of the best.

This has been the worst week for Celtic in quite some time.