Postecoglou has regularly come under pressure for his high-energy, high-risk and no-holds-barred style, but said he “wouldn’t move an inch, mate” because of his view of the game.

Celtic secured two points from 18 in the Champions League this season.

Domestic dominance was the safety net that trumped European failure. Spurs have no such scope in the brutal terrain of the Premier League.

Celtic have evolved a bit since Postecoglou’s departure and have found a style of play that suits them better on the unforgiving pitches of Europe.

But Postecoglou’s return will leave some fans wondering what might have been if he had never received an offer to go south.

Would he have optimized his natural instincts for the greater good, as Rodgers did, or would Celtic still try to keep up with all rivals, as they have done under his watch, with poor results?

The answer probably lies in what we see from Spurs’ boom and bust – good enough to keep Aston Villa, Manchester City and Manchester United in their place, but also soft enough to add goals and points late in the season achieve a list of games over which they had control.

As much as Celtic fans loved having him, they probably realize by now that they had to lose him in order to progress in Europe, the real proving ground for a team that has mastered Scottish football.

Because it’s Postecoglou and because it’s Rangers, half of Glasgow will be white on Thursday. They will always appreciate and support him, but in the new world Celtic seem to be moving into, the days of feeling sorry for him are over.