Maurizio Sarri's side was desperately poor at the Groupama Stadium, failing to register a single shot on target.

Lucas Tousart scored the only goal of the game after 31 minutes and Bonucci has slammed Juve's approach in the opening period. 

"We got the first half wrong," he told Sky Sport Italia. "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."

Defender Danilo was in agreement with his captain and says Juve 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."