The Viola were beaten 2-1 in a big grudge match on Tuesday evening, but were particularly under the cosh in the first half.
"I was ashamed of those first 45 minutes in Turin. I was just as upset as the fans," said the under-fire Coach.
"Yet I had told my players that these are the games you'll regret, so you have to play them to the max. Then there was a problem because our three midfielders had never really played together before. The whole team lacked character, though.
"If you don't have character, then you can't buy it. Watching the Juventus game back, I just couldn't believe my eyes. I never expected such a reaction. I don't understand why, because they trained well and prepared the match in a certain way, but couldn't do anything.
"Nobody took responsibility, nobody made themselves available, although we did react in the second half. I cannot explain it, but we must never repeat that performance again."