Callum McGregor says Celtic were “miles off” their usual level as they suffered their heaviest defeat of the Ange Postecoglou era.
The Hoops were soundly beaten by Old Firm rivals Rangers at Ibrox on Saturday in the final derby day of a season.
Despite an outstanding season, and a eighth domestic treble only win away, the newly crowned Scottish champions will be hurting after losing 3-0 to their city rivals.
Goals from Todd Cantwell, John Souttar and Fashion Sakala mean Michael Beale recorded his first win in the derby since taking over from Giovanni van Bronckhorst at the end of last year.
And the Celtic captain admitted they will have “take our medicine” it was a major off day for his men.
He said: “We were miles off our usual level, and that’s what happens, you’ll lose this kind of game if you are not at the races.
“We gave ourselves a lot to do, they scored at important times of the game and that took the game away from us.
“But we have to take our medicine and admit we were poor, we didn’t deserve anything from the game and we have to accept that.
“We just didn’t perform, we weren’t at the level that we normally are and if you turn up and perform like that then you don’t deserve anything out the game.
“I think home advantage in this fixture always plays a part, especially when they score early, it gives them a lift, it gives the crowd a lift and we made it difficult for ourselves. At times we have been able to come back from that I don’t think there is much else to say other than we had a bad day, we didn’t perform to our usual level and the defeat is a result of that.”