Ange Postecoglou took responsibility for upsetting the Celtic fans after their shock 1-0 defeat to Livingston.
Andrew Shinnie’s strike condemned the Hoops to a third league defeat in six games and left them sixth in the Premiership table.
It rounds off a tough week for the Celtic boss, who saw his team throw away two-goal lead in Thursday night’s 4-3 defeat to Real Betis in their Europa League Group G opener.
Postecoglou admitted his side didn’t start how he expected them to and fell into a trap.
"We didn't start the game well and we paid the price for trying to ease our way into the game,” he told BBC Scotland.
"We didn't start with the aggression or the positivity that we have in other games this year.
"After they scored we dug ourselves into a bit of a hole. We tried hard enough but our decision making in the final third was pretty poor."
Postecoglou was quizzed by the Beeb’s Kenny McIntyre on not testing the Livi ‘keeper enough, and was given a curt reply: "No, but that is what I just said."
That was followed up with a query on whether it was a concern: "It's a concern today, but it hasn't been a concern all season, Postecoglou replied.
"We didn't start the game with the intent we have so far. We fell into the trap of thinking we couldn't play our football today.
"When you are not aggressive enough and you are not positive enough in your outlook you give the opposition a chance to get into the game."
The Australian continued to disagree with McIntyre’s line of questioning when it was suggested there’s been a lack of consistency from Celtic this season.
He replied: "No, I don't think that's fair.
"I think it's been consistent and we have played well in every game. Today was the first day where I didn't think we played our football.
"If you are talking about inconsistency, I guess there has been in results, but our supporters have been fantastic and I bear a huge responsibility for sending them home disappointed.
'The job now is to pick them up and get a good result on Thursday."
