"We never stop".

It's the mantra that has served Celtic well since Ange Postecoglou rocked up as the manager in the summer of 2021. It turns out his players are only human and they do stop now and again. They would have wished they didn't drop down the gears at Ibrox of all places but Celtic never really got started against Rangers as they slipped to a 3-0 defeat.

It was a rare loss as they succumbed domestically for only the second time in the campaign. A marker laid down for next season? An eye-opener? A wake-up call? It was multiple choice answer E - none of the above.

This was a Celtic team who started minus three of their recognised defensive back four - Cameron Carter-Vickers, Alistair Johnston and Greg Taylor Also, the visitors began the match without the talismanic Kyogo Furuhahshi and workhorse Daizen Maeda. They also handed game to a number of players who have not been regular starters this season such as Alexandro Bernabei and Liel Ababa.

Postecoglou would never throw his players under the bus but he admitted that too many changes might have thrown the champions out of kilter. Although some of the fringe players - mainly Bernabei, Kobayashi, Abada and to a lesser extent Oh - may have a bit to go to convince the manager and the fans that they can force their way into the starting eleven.

READ MORE: Premiership champions Celtic fail to turn up against Rangers at Ibrox

As the Australian told Sky Sports: "We did not really perform at the levels that we needed to today. The amount of changes I made probably didn't help in terms of the guys lacking a little bit of sharpness. At the end of the day we just weren't good enough."

Not good enough. Three words rarely associated with Postecoglou's Celtic. The defeat at Ibrox was arguably the worst performance under the 57-year-old since he arrived at Parkhead.

Postecoglou, though, will see the bigger picture here. By throwing in some of his fringe players to the cauldron of Ibrox in the aftermath of a wretched result, he will be already assessing the areas where Celtic need to strengthen if they are to make a fist of the group stages of the Champions League next season. Perhaps the much-lauded strength in depth of the Celtic squad is not all that is made out to be and more Champions League-ready reinforcements are needed for the next evolution of the side to take.

Celtic Way:

On the basis of this evidence if Rangers are the only opposition that you face domestically who could be called a 'Champions League level outfit' then Postecoglou will certainly know that some of those players given a chance at Ibrox are clearly not up to the job.

You get the feeling that this was the plan all along. Wait until the league was done and then throw in the fringe players to test them in the toughest conditions possible. They don't come much tougher than Govan with no backing from away supporters.

Result wise many supporters will claim that the manager made the wrong call. Evolution-wise, I am utterly convinced that the Aussie called today's team selection spot on. The smart money is on this move being done by design. Postecoglou can justifiably go to the Celtic board this summer and say that his team are still short of being a real Champions League competitive outfit. He can also presumably justify the jettisoning or culling of some half a dozen players or more whose futures will undoubtedly lie away from Celtic. Watch out for all of the deadwood at the club being shipped out over the summer.

Having guided Celtic into the Champions League group stages for two consecutive seasons Postecoglou has credit in the bank with those at boardroom level. The club also have the cash reserves to fund a modest splurge on players that will help the manager take his team forward, particularly on the European stage.

They say that you learn more about your team in defeat. Postecoglou was asked that very question in his post-match interview. His response was telling: "I learn all the time mate, you never stop learning."

As for the game itself, it was reminiscent of Tommy Burns' side in 1994-95 during the season when they rented out Hampden Park. Rangers were wracking up the trophies and had won the league when Celtic dismantled them 3-0 at the national stadium. It really meant nothing then to home fans and while the victory was lauded, it felt like a hollow celebration.

It's the same here as Rangers inflicted a loss on Celtic for the first time in six attempts but their supporters shamefully pelted Portuguese superstar Jota with objects which is not on. While Rangers' victory ultimately means nothing in the grand scheme of things, they will toast their success but it will be hollow. They, like Celtic in 1995, failed to turn up in the games that mattered this season.

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The title has been won and Celtic are homing in on a world record eighth domestic treble. The record points tally for any Celtic team in history also bit the dust on a day to forget. Winning dead rubbers doth not world beaters make. The irony in all of this is that both Glasgow giants are embarking on rebuilds this summer. Rangers' rebuild is to try and make sure that they can hold on to Celtic's coattails and compete for the major domestic prizes regularly once again.

Celtic's rebuild or evolution is one for Postecoglou to ponder as he sets about turning them into a force in Europe. Qualifying for the Champions League group stages back-to-back is rightfully regarded as a success but is it enough to satisfy his lofty managerial ambitions?

If Celtic "never stop" and Postecoglou never stops learning then he'll deal with the defeat in a dignified manner that has been the hallmark of his two-year tenure so far. He, of all people, will know that Celtic were not exactly stopped at Ibrox they were just temporarily halted.

If Postecoglou learned any lessons from the defeat, then moving forward it will be making sure that never again he will be able to deem his team not good enough.

Not on his watch, mate.