‘Teacher’ Martin O’Neill with work to do as Celtic taught another lesson

The overriding questions remains, though. How long will O’Neill have to improve Celtic?

His return, alongside assistant Shaun Maloney, has brought back a feelgood factor but that was only going to last so long.

The laughs had over O’Neill’s matchday fit have faded, while Celtic’s deep-rooted problems have returned in stark fashion.

Captain Callum McGregor was at the heart of the happiness on Sunday, scoring in the extra-time win, but he was quick to assure no-one had got carried away.

“Nothing’s been solved after a really good game at the weekend,” the midfielder said after defeat in Denmark. “We know that we don’t get too up or too down.

“We come away here against a really good side, a good club, who do a lot of good things and they know what they are.

“There’s a lot of growth still left in our team as well. We know where we are and we know where we want to get to.”

It appears Celtic are far from the latter, and it’s lined up to be an almighty task to get them there.

On a sobering night, it’s not the interim manager who will take the heat. It’s not even the players being taught by him.

It’s the board who have managed to quieten the clamour aimed in their direction for a few days who will be feeling the pressure once more.