Neil Lennon castigated his defence after Celtic's shock 3-2 defeat at Inverness left Old Firm rivals Rangers in pole position in the race for the Clydesdale Bank Premier League title.
The Celtic boss, who revealed that midfielder Beram Kayal came off in the second half with suspected concussion and a suspected broken wrist, pointed the finger mostly at his defence, saying: "We are better than that. We have been very good defensively all season but the back four were really poor the second half.
"I might have to change the back four after that performance, I will assess it on Thursday and Friday."
He added: "Some players picked of all days to have their poorest game of the season.
"The two full backs were poor.
"The two centre halves were poor and the two centre forwards were eachy-peachy (both as bad as each other).
"You can't have that many off form and get a result and we didn't need to win the game.
"Defensively we were very poor and if you play like that you don't deserve to win any game.
"At half-time, we told them to brush up defensively but we have gone missing for the third goal.
"It was a great finish but we didn't put a glove on him."
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