Maurizio Sarri has slammed the pedestrian passing of his Juventus players as they fell to a 1-0 defeat to Lyon in the first leg of their Champions League last-16 tie.
The Serie A leader was insipid at the Groupama Stadium and had no answer to Lucas Tousart's solitary strike in the 31st minute.
Cristiano Ronaldo huffed and puffed in attack, but was powerless to prevent Juve ending the game without having registered a single shot on target.
Sarri cut a frustrated figure and says he was stunned at how slowly his side moved the ball in comparison to how it did in training ahead of the game.
"It's difficult to explain why, but in the first half we moved the ball too slowly so the opposition were going to press, win the ball back and score," he told Sky Sport Italia.
"We lacked determination and aggression when attacking, and for 15 minutes lacked it defensively too.
"The second half was better, but it's not enough for a Champions League match. I don't know why I cannot get the players to understand the importance of moving the ball quickly.
"This is fundamental. We'll keep working on it and sooner or later this concept will get into their heads.
"I continued to tell them, and there were many who were doing it, moving the ball too slowly and therefore getting into the wrong positions.
"We had training yesterday and the ball was moving twice as quickly as it did tonight. This is the opposite of what should happen. Lately we're doing a lot of things opposite to in training.
"When the ball is slow, you lose positions, you allow the opposition to close you down, to be aggressive and steal the ball back.
"I don't even think the Lyon pressing was that strong. We just moved it slowly, never varied the tempo, and when you do that, it's unlikely you're going to create anything."
Centre-back Leonardo Bonucci also slammed Juve's approach in the opening period.
"We got the first half wrong. We were second to every ball. In some games, you pay for the tiniest error. We were too stretched out, not aggressive enough and that is an issue of mentality. We should've woken up earlier.
"I could tell something wasn't switched on with the 11 starters. We've got to sort this out as these are the things that make the difference.
"Now we have to get our heads focused on what awaits us on Sunday [a Serie A clash against Inter], then we absolutely must qualify in the second leg."
Full-back Danilo was in agreement with his captain and says Juventus will need to replicate its second-half display if it is to qualify for the last eight.
"We cannot just gift the first half to the opposition in such an important tournament," he said. "We are aware that we did that and need to work harder.
"We must always play with the aggression that we showed in the second half when we kept the ball practically the entire time and showed more courage, more initiative.
"Playing in front of our fans in the second leg, it is our obligation to press, push, score, win and qualify for the next stage of the competition."