A bad day at the office, but one Anthony Ralston is adamant cannot allow themselves to repeat.

It certainly doesn’t help when that off day comes at Ibrox. Ange Postecoglou’s Premiership champions were well short of the relentlessly high standards they have set for themselves this season, and were swept aside 3-0 by Rangers.

Postecoglou had made six changes to the side that clinched the title at Tynecastle last week, but players and manager have said that cannot be used as any kind of excuse, not least given their rivals’ line-up was just as unfamiliar. It is a result which must be viewed in context, of course, given Celtic had already been confirmed as league champions, but Ralston’s dejected demeanour as he spoke afterwards put paid to the notion that there is any such thing as a meaningless derby when you’re out there on the pitch.

It was suggested that, after the euphoria of last week, there may have been a subconscious drop-off among the Celtic squad, but Ralston maintains that can’t happen.

READ MORE: Callum McGregor brands Celtic defeat 'unacceptable'

“I wouldn’t like to think so, no,” the right-back said. “It’s been completely drummed into us that every game is a new game. It doesn’t matter what we have done, it doesn’t matter what credit you have got in the bank.

“It’s about each game no matter what game it is performing to the level that we want to perform at. On the day and any other day, it is not acceptable.

“No matter who comes into the line-up, we are all quality players. 

“At Celtic Football Club, you are expected to be at the highest level at all times when you are called upon. So we will not use any excuses.

“We were not at our best, first and foremost. We have to be honest with ourselves.

“We have done absolutely terrific this season and we are champions for a reason because consistently over the course of the season we have implemented how we want to play.

“It quite plain and simple, we didn’t do that. We move on from it, but we analyse it.”

Callum McGregor used that same word – ‘unacceptable’ – in the aftermath, and believed it would serve he and his team-mates a timely reminder that they cannot always assume Rangers will remain in their rear-view mirror.

Ralston agreed it was a result and performance that mustn’t be repeated.

“Exactly,” he said. “And we do know that. We have our standards and we are not going to hide away from that. It’s not in our nature.

“We have not got to the position we have got to now by hiding away from things and by accepting things. By just sitting it aside.

“We face value absolutely everything that we have done from day one and we’ll continue to do that.

“Football will always remind you. But I feel we have a great group of lads.

“We have had so much success, but, like I said, we don’t dwell on that success. We have a changing room of lads who want the best at all times, the best standard, no matter what game.

“This will be dealt with, it’ll be analysed and then we can move on.”

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Celtic did have their chances on the day, with Oh Hyeon-Gyu hitting the post mere moments after Todd Cantwell had given Rangers the lead. Liel Abada didn’t quite get hold of a cut-back near the penalty spot, and Matt O’Riley was denied by Robby McCrorie after driving through the Rangers backline.

“We had our chances and that is part of our analysis that we had to take our chances and we didn’t do that,” Ralston said. “That’s another part. But, like I have said throughout this conversation, we have our standards and we don’t accept anything less than the standards that we want to produce on a weekly and game-to-game basis.”

Celtic have made a fine habit of capitalising on the big moments in these matches this season, with Rangers manager Michael Beale even remarking he felt like every big chance created against his side in derbies had resulted in a goal.

But that script was flipped somewhat on Saturday – Celtic didn’t make their opportunities count, and Rangers did. For Ralston, it was evidence of the ultra-fine margins that can decide these fixtures.

“Exactly,” he said. “And this is football. But, again, where we have got to at this point is through our hard work. Through not accepting our standards dropping. Through relentless training, relentless high standards that we have attained through a course of time.

“So it’s not an excuse to cut ourselves any slack. We want the best at all times and we take this at face value.”

A poor day indeed, but one that could be forgotten about entirely in just a few weeks’ time. Celtic have three league games remaining before the small matter of a Scottish Cup final against Inverness Caledonian Thistle on June 3. Victory at Hampden would clinch the club an unprecedented eighth domestic treble, and cap what has been a hugely successful season already.

And Ralston is keen not to lose sight of that fact, despite his obvious disappointment at the weekend.

“We can’t forget that,” he said. “We can’t forget that we are champions for a reason. We have been outstanding this season and we are all really happy about the season that we have had as a collective as a squad.

“We have the Scottish Cup Final to look ahead to and there are a lot of positives still to take. But that doesn’t mean anything is accepted. 

“Nothing is accepted but the high standards that we have created, that we have set and we will be looking to maintain that moving forward.”