The Dutch champions swept the Premier League holders aside with ease on Wednesday night.
“It was probably my fault because I prepared badly for this game,” Mancini said.
“I didn’t prepare the players and I’m at fault. When you prepare for a game sometimes it is a different to what you expect. Sometimes you think the game goes one way and it goes another. We played a bad game. We had a few chances to score but the players didn’t really play well.”
