City boss Mancini said: "I think Rafa is a good manager, he doesn't deserve all these bad things that he has there. He has worked hard and worked well for Chelsea.
"Football is strange. But he is still one of the best managers."
He said: "I played one friendly under him when I was 16 against Castillon nine or 10 years ago.
"Of course, I've followed his career very closely. He's a very, very good manager.
"I saw what he did when he was at Liverpool. He's a great manager. I haven't worked that closely with him but I know he's studied the game.
"He's into the tactical side of the game and is very creative. He analyses football massively."