There is still a second leg for Luis Enrique’s side to turn the tie around, but they face a mammoth task to keep their continental dreams alive.
Questions are being asked of the playing and coaching staff in Catalonia, with Barca also off the pace in the La Liga title race as an era of dominance hangs in the balance.
Sacchi believes the aura of invincibility has disappeared around a once formidable outfit, with Lionel Messi even considered to have lost some of his spark.
“The Barcelona King is dead,” Sacchi told La Gazzetta dello Sport.
“There is another sovereign who continues to impose his rule, Real Madrid, but [there is] also space for a newcomer to slip on to the throne.
"I see Juventus perfectly suited for that role. They are improving and, at the moment, are the favourites along with Real Madrid to take the trophy.
"For some time, Barcelona have not been the old Barcelona. In La Liga they also beat the weak clubs with ease, but struggle with stronger sides. You no longer see that aggressive, organised and hungry team we so admired.
“The Catalans dominated for 10 years, imposing a style of play that was at times truly marvellous. They gave a football lesson to the whole world.
“Now they’ve hit a brick wall and even Leo Messi can’t skip past his man anymore, because the whole machinery of the team is broken down.
“I always say that to succeed you require, in order of importance, a club, good football and the players. Without an idea of what football to play, the individuals will get you nowhere.”
Sacchi added on the Italian champions: “Juventus have a strong club with clear ideas. Their coach Max Allegri is capable, intelligent and efficient, with players who interpret the instructions well.
“It’s true I criticised Allegri, because I knew he could give more. He wasn’t very generous in terms of entertainment before and was too prudent. He did the bare minimum, a goal and then clam up.
“Now his team seeks more goals and is aggressive.”