Ange Postecoglou admits Celtic accepting their fate was the biggest disappointment in their 3-0 defeat by Rangers at Ibrox in the final Old Firm game of the season.
The Hoops went into the game as cinch Premiership champions following their 2-0 win at Hearts last week and had been unbeaten in five Glasgow derbies this season.
However, goals from Todd Cantwell, John Souttar and Fashion Sakala gave the Light Blues their first win in seven meetings between the Glasgow giants.
Celtic remain on course for a domestic treble, with the Scottish Cup final against Championship side Inverness at Hampden Park to come on June 3, but Postecoglou spoke about the back-to-back away fixtures post-split in the league as he analysed only their second league defeat of the season.
He said: “In the second half I felt we almost accepted our fate – you can lose a game of football, that will happen – rather than us going out there and trying to change the course of the game.
“Yeah (it was the biggest disappointment).
“They are human beings and they have had an outstanding season and the euphoria of last week and winning (the league), it is kind of weird winning it and with the fixtures, you have to play away again.
“You don’t really get a chance to appreciate the moment but welcome to Celtic. That’s the expectation, that is not going to change.
“It wasn’t a great performance, disappointing performance, disappointing outcome.
“There was a couple of moments when we really should have scored and at least taken some momentum out of the game but we never got a foothold.
“In the second half we never really made an impact, there was a bit of desperation about us trying to get into the game rather than playing our football.”
Moments after the immense Cantwell fired the ball through the legs of Celtic keeper Joe Hart, Celtic striker Oh Hyeon-gyu, chosen in place of Kyogo Furuhashi, was set up by Liel Abada.
However, with only Gers keeper Robby McCrorie to beat, he chipped the ball off the post with the home defence recovering.
Postecoglou said: “It is a big moment, absolutely.
“They were up for it, the crowd were up for it and they got the goal and if we can hit back straight away it takes a bit of the momentum out of them.
“It is a goal the big man probably should have put away, he hit the post so he wasn’t far off. It is a bit of learning for him as well.
“When he looks at somebody like Kyogo Furuhashi, he misses goals too but he doesn’t let it affect him, he is still running his socks off for the team.”
There were no Celtic fans in the stadium due to “safety and security” issues, as was the case for Rangers when they visited the east end of Glasgow in April, but Postecoglou did not use that as an excuse.
He said: “I don’t think the fans could have done anything about our performance. It is not the first time we have played here without fans.”