Gianluca Zambrotta spent two years at Barcelona
Former right-back Zambrotta has played for both clubs but he was left shocked at the way Barca conducted themselves last week.
Paulo Dybala’s double helped Juventus to a 3-0 win in the Champions League quarter-final first leg – a game where they played Barca off the park.
Zambrotta told Marca: "I was at the game and I did not think the problem was [Javier] Mascherano, [Gerard] Pique, or Neymar.
"This year they have failed a lot away from home; at Paris Saint-Germain, Malaga, Deportivo La Coruna, Juve.
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“The difference with Juventus was mostly attitude.
"Let's not forget the urge to press that Juve had. When Barcelona play at the Camp Nou, as with the game against PSG, we see a different team.
"Barcelona did not have a tactical problem, but one of mentality and attitude."
Barca pulled off mission impossible to beat PSG 6-1 in the last-16 but Zambrotta isn’t expecting a repeat.
He added: "Juventus' attitude is not like that of PSG.
"In the last nine Champions League games they have only let in two goals.
"They defend very well, with respect to PSG. Barcelona have to be very offensive but Juve are very strong with [Paulo] Dybala, [Gonzalo] Higuain, [Juan] Cuadrado… and I do not think they will play defensively.
"I am sure that they will not come to only defend at the Camp Nou. There is no perfect plan, they must play as they always do, as a compact team where everyone runs and helps one another."