From the high of a treble, to the realisation the end of an era had arrived in little over 24 hours.

A painful goodbye to Ange Postecoglou was not just an emotional rollercoaster for the fans who adored him, but the players who gave him everything over two trophy-laden campaigns. Few, though, will be as grateful for his leadership as Joe Hart.

The veteran former England goalkeeper’s career had slid into the doldrums since his Manchester City career slid away from him, bouncing from loans at Torino and West Ham into two permanent, but disappointing, spells at Burnley and Tottenham. But when Celtic needed a goalkeeper in the hectic summer of 2021, it was for Hart that Postecoglou came calling.

Five trophies and a career renaissance later, a lasting mutual respect had been formed between player and manager. Hart confessed to experience ‘all sorts of emotions’ when Postecoglou’s departure for Spurs was announced, but the 36-year-old has been thrown enough curveballs in football to realise the only for it is to adapt and overcome.

Getting Brendan Rodgers back through the door was certainly one way of doing that, and Hart is confident the Celtic machine will roll on and on.

“I think you go through all sorts of emotions, don’t you?” he said. “I really got on with and appreciated Ange as a person. I really, really respect him as a coach and as a manager.

“I think he’s exceptional and one of the best that I have ever worked with.

“I have said it before, you know what football is like. There are times when things shock you and sometimes when you are emotionally taken by something.

“But then the next day rolls on and, once it is official, then the new manager search goes on and everything changes. You adapt and you go on.

“I’ve spoken to him and wished him all the best. I’d like to think that is something that, in five or 10 years time when we bump into each other, we can talk about.

“But right now he has got work to do and it’s the same here.”

Hart’s first conversation with Postecoglou was a brutally honest one. Failing to find a new home after City had left him disillusioned with the game to the extent he hadn’t ruled out quitting.

Postecoglou helped Hart feel part of something again, and he’s so content in his current surroundings that no such talks will be necessary with Rodgers.

“That part has passed,” the keeper said. “With Brendan coming in and a lot of the staff being the same, I think I am understood. I wasn’t necessarily understood, I don’t think, in the couple of years that didn’t go as well on paper for me and I don’t mean that in that I struggled, or people were rude to me.

“It’s just football was a little bit indifferent for me at the time and I needed to have an honest conversation at that moment. I did.

“Luckily Ange responded and understood me. And I’m up here now, I’m settled and I am feeling good. All I want to do is get back and that message is pretty clear.”

Given Hart’s age, it is only natural there will be speculation over who might succeed him between the sticks. But he is adamant he won’t be knocking on Rodgers’ door seeking assurances that he currently remains first pick.

Hart feels that to do so could be interpreted as a of insecurity and, ultimately, detrimental to his career and the team. Instead, he simply plans to knuckle down and graft to keep his place like every other member of the Celtic squad.

“Those conversations you never have,” he insisted. “You’d get lost if you wanted to have those. That is almost an insecurity.

“Like I say, I’m just going to offer my best. I have quite a lot behind me that puts me in decent stead, but I don’t rely on that at all.

“Every single one of us is going to be pushing. The moment you rest is the moment you struggle.”

Does that mean it’s going to be a case of Hart proving himself all over again?

“I think I kind of feel that every day,” he replied. “I don’t need to prove anything, but I want to. I want to push every single day, I want to give my best and give someone a decision to make.

“I have learned over the many years that is all I can offer. However someone wants to take it and whatever decision they want to make is completely up to them and that’s why people get paid the big money to be in charge of football teams.

“But I know all I can do is give my best, show my best and see where that takes me.”

From the mooted candidates following Postecoglou’s departure, there can be little argument that Celtic have recruited the most qualified, experience and proven. Rodgers enjoyed unprecedented success during his first spell in charge, becoming the first manager to win two consecutive trebles, the first of which was delivered without losing a domestic match all season.

With Rangers in the midst of a significant rebuild across the city, Rodgers’ mere presence further consolidates Celtic’s position as favourites to retain the Premiership title next season. But Hart is cautious not to use the past as a predictor of future success.

“I think it would be naive of me to say that just because Brendan is here,” he said. “And I think he would say exactly the same. What’s gone is gone. It is exceptional what has gone on in his past, especially as a Celtic manager.

“But we have a whole brand-new job on our hands come August 2023. That is when we have got to make it happen.”

Having won it all last season, the expectation will be that Celtic do it all over again when the new campaign commences in August. For Hart, drawing a line under past achievements is key to maintaining the hunger for more.

As far as he’s concerned, Celtic may have swept up every trophy in 2022/23 but when the first whistle blows on a new campaign, those titles don’t belong to them anymore.

“Look we’ll see,” Hart said when asked if last term will be difficult to top. “Obviously, that is our intention.

“When we beat Inverness on the last day of the season, we all got together and we were happy and then we went our separate ways.

“Some boys internationals, some boys on holiday, then we rocked up on Monday ready to go again.

“Obviously, we have got some titles to defend, but we don’t necessarily own them anymore. They are all up for grabs.

“All the competitions start again and we are going to push and go hard to try and be involved and right at the top again.”