The Catalans were destroyed by Paulo Dybala, who scored two stunning first half goals and Giorgio Chiellini added another with a header in the second half of their Champions League quarterfinal first leg on Tuesday.
Barca now have to repeat their heroics in the previous round when they managed to overcome a 4-0 away defeat in the first leg if they want to advance to the semifinal.
And Iniesta says: “We did some bad things, mainly in the first half.
“The Champions League punishes you with these two goals.
“In the second half we saw something different. We deserved to score one goal but that doesn’t help now.
“Juve are a good team but when you don’t do things well, you are penalised a lot.
“The feeling is not as pessimistic as it was in Paris but once again we have a real uphill task in a knockout game.
“If we do things as we have to, we’ll be back in the tie. If not, it will be impossible.”
Coach Luis Enrique is not a hopeful after seeing Juve’s defence bossed his superstars.
He says: “This time, it’s more difficult to believe in a comeback.
“It was like reliving a nightmare.”