Nine months on from the conclusion of a season which saw Celtic finish an embarrassing 25 points behind Rangers, the sense of a pendulum swing is impossible to ignore. The finest 90 minutes of Ange Postecoglou’s reign saw Celtic maul Rangers, with the added benefit of moving past their city rivals at the summit of the Scottish Premiership. Incredibly, given the earlier gulf between the teams, Celtic now have to be the favourites to win the league.It felt appropriate that Reo Hatate, a player coaxed from Japan to Celtic on account of Postecoglou’s direct knowledge, was central to this success. Rangers had nobody on display to match the midfielder’s level of influence. Giovanni van Bronckhorst has Aaron Ramsey to introduce to the fray at some point but this was a bruising night for Rangers and their manager. For all Celtic’s progress, there has been obvious regression at Ibrox. The outcome here was in no way flattering to Celtic, who played with a confidence level of champions in waiting.“I am really proud of the group,” said Postecoglou. “Right from the start they were outstanding. That was everything we want to be as a football team.” There followed a warning. “Our end goal is to play football a certain way but win things. We haven’t done that yet.”Celtic entered this fixture having failed to beat their oldest foes since late 2019. Progress under Postecoglou has been obvious but the manager is experienced enough to comprehend judgements are made on marquee matches. Given the momentum gathered by Celtic in recent months this felt like Postecoglou’s opportune moment to deliver. And, boy did he.Celtic were desperate for a positive opening and duly claimed one. There was – naturally – controversy attached to the opening goal, beautifully angled home by Hatate from the edge of the penalty area. Rangers complained bitterly that the referee, Bobby Madden, should have stopped the game following a clash of heads between Calvin Bassey and Joe Aribo as they tried to clear a Matt O’Riley corner. Bassey was lying on the turf as, seconds later, the Japanese midfielder sent Celtic Park into raptures.Debate over the legitimacy of the goal will run and run. What cannot be denied is Celtic started the game by far the better team. Allan McGregor in the visiting goal produced a stunning double save from Jota and Giorgos Giakoumakis in the 15th minute as the hosts looked to double their lead. McGregor, days after his 40th birthday, denied Giakoumakis twice more before the half hour. Rangers lay firmly on the ropes, their only opportunity of the first half seeing Joe Hart race out to beat Scott Arfield to an Aribo pass.Reo Hatate scores the first goal of the game. Photograph: Jason Cairnduff/Action Images/ReutersThat opening arrived just moments before Celtic claimed the second goal their dominance fully merited. Hatate again claimed it, this time with very little backlift from 20 yards. McGregor, diving to his left, was totally helpless.There was more to come from rampant Celtic before the interval. Hatate’s next trick was to deliver a glorious cross from the left, which found the Rangers defence completely static. Liel Abada took full advantage to prod beyond McGregor. Celtic did not want the half to end; Rangers desperately needed any form of respite.Having watched Rangers ship three goals in back-to-back league games for the first time since 1986, Van Bronckhorst used half-time to make a triple substitution. Amad Diallo, the on-loan Manchester United forward who spent 45 minutes resembling a little boy lost, was understandably among those removed. The switches did afford Rangers a little more prominence but only that. Fashion Sakala and Arfield spurned their finest chances for consolation, with Ryan Jack cracking the crossbar from range. Celtic gave the impression of playing comfortably within themselves.McGregor tipped an O’Riley free-kick over as Celtic closed the game in pursuit of a fourth. That it did not arrive failed to perturb anybody in the stands. The stars had been in hoops.