David Wagner described Huddersfield Town's 4-0 defeat at Bristol City as their worst performance of the season.
He revealed leading scorer Nahki Wells has a knee injury which could keep him out of the final match of the season against Brentford.
But the head coach was seething about Town's display at Ashton Gate.
"After our worst performance of the season we have to show a performance with the right attitude and character (against Brentford)," he said.
"I think we have to give credit to the lads for much of what they have done over the last six months, but we didn't take our identity onto the pitch in this match.
"We made a lot of mistakes in all areas and we played like 14 individuals against a team.
"We had too much distance between our lines, and we weren't aggressive and strong enough with the ball when we needed to be.
"There was not enough speed, so we missed more or less everything of our identity.
"When we play like this we have to accept questions about our motivation, so we have to be honest with ourselves and show the right reaction."