Are Celtic reacting quickly enough to the ‘wake-up call’?

As O’Neill threw himself into planning the new campaign, he had little time to digest last season’s success.

Celtic secured their 14th Premiership crown in 15 years in remarkable fashion, winning their last seven matches to snatch a title that at times seemed out of reach.

“I’m like, no it didn’t (drown),” O’Neill said.

“If I wasn’t at the football club anymore, I think I would have had more time to digest it and say, oh that was really great, surreal.

“It feels like you’re back again, and so I probably haven’t had time. Maybe the first league game at Celtic Park, maybe I’ll think about it then, but to be honest, no I don’t think it’s really sunk in.”

The hectic, draining nature of the job and the title win left O’Neill unsure whether to take over full-time this summer. But the prospect of regret pushes him back to the dugout.

“It was weird in the sense that if I had been asked about it a day after we did it, I don’t think I would have had the energy,” he said.

“And I think really deep down, if I feel right at the end of July, August or September and things go on without me, then you think, oh God, maybe I want to stay.

“So I tried to push myself a few more months.”

The incentive of the Champions League also played a role. Celtic’s play-off tie looms large – the first leg will take place on August 18 or 19 – and O’Neill is well aware of the importance of the competition to the club.

Celtic, then under Brendan Rodgers, emerged from a disastrous qualifier in Kazakhstan’s Kairat Almaty last summer to set the tone for their torrid season.

“Absolutely vital,” O’Neill said of reaching the league stage.

“If we’re going to do that, firstly, we’re talking about trying to increase the squad. Secondly, it’s preparing the players physically and mentally for those games, and that becomes very important.

“The disappointment of last season, not getting into the Champions League because of a good run the year before, I think that carried over into the league performance. Malaise is a very strong word but frustration and anxiety about everything and as a result I think we fell down a bit but we picked it up in the end.

“Now this tie that we have, whoever it is, has become very important.”