Rotherham boss Steve Evans said his side's "unacceptable" defeat at Port Vale on Saturday stemmed from under-par performances in training.
The Millers lost 6-2,
having found themselves four down after 30 minutes.
"I think our back four and our central midfielders looked all over the place," he told BBC Radio Sheffield.
"I'm not a manager to come out and blame my players but it was wholly unacceptable and we'd seen the signs of it in training on Thursday and Friday."
He added: "We reminded the players that it wasn't at an acceptable level and it carried on into the first half an hour of the match."
Evans wants the side to move on quickly from the defeat, which leaves them in 10th position after five games.
"We need to learn from it and put it behind us," the former Crawley boss continued.
"We have to take this on the chin and regroup and it's important we are all focused for next week."