Celtic manager Neil Lennon refused to pull any punches after seeing his side surrender the upper hand in the SPL title race against Inverness.
The Bhoys could have returned to the top of the table on Wednesday with a point at Caledonian Stadium, but slipped to a shock 3-2 defeat.
Celtic were all at sea defensively and Lennon admits the whole of the back four were poor as Inverness' attack ran riot.
The visitors were level at half time but two superb finishes from Grant Munro and Shane Sutherland ensured Rangers moved back into the driving seat in the title race.
Lennon also criticised the club's frontline with both Gary Hooper and Anthony Stokes coming under fire for their lightweight display.
"We are better than that," said Lennon. "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.
"Some players picked today of all days to have their poorest game of the season. The two full-backs were poor today.
"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.
"There are no excuses. We gave them all the warnings and told them what might happen and we responded very well after the first goal."
If Rangers win their final three matches they will be crowned champions for a third consecutive season, although Lennon is crossing his fingers there are more twists and turns to come.
"The title is in Rangers' hands," he continued. "They are a point ahead and we have to win all our games and take it to the last game of the season and see what happens.
"If teams are as committed against Rangers as Inverness were against us, then there might be (another twist). Anything can happen on a given day but I didn't want this to be the given day.
"We let ourselves down, not just the players but myself, Johan (Mjallby) and Alan (Thompson) will have to take criticism. We might have picked the wrong team."
Who will win the SPL title?