"Teams down at the bottom, if they take the lead, invariably sit back," said the Reds boss.
"We showed a lack of confidence against Crewe in that we dropped deeper and deeper and invited trouble which was our undoing on Saturday. It cannot happen again.
"We have to concentrate on things we can influence and not on Coventry's game. We have to give our everything.
"We have to stand up, be counted and prepared to battle.
"Anybody who thinks it is going to be like a testimonial encounter will be put right after two or three minutes.
"If I have got anybody who is not prepared to battle they need to tell me early and make sure they do not get on the bus."