Jerzy Dudek has labelled Rafa Benitez a 'genius' coach who was not great with people.
The Polish goalkeeper played under the Spaniard at Liverpool between 2004 and 2007 and despite winning the 2005 UEFA Champions League together, there was a strained relationship.
In his new autobiography, 'A Big Pole In Our Goal', 43-year-old Dudek recalled his time at Anfield under Benitez who he describes as a 'cold' yet clever manager.
"Rafa Benitez is truly passionate about the game," wrote Dudek of the current Newcastle United boss.
"He has a great knowledge of football. He's not a fool who comes out with theories that are all talk. His problem is that he's not a great 'people person' so always encounters problems when managing a group because he is very cold and hard-faced in how he makes decisions.
"He kept a distance between himself and his players – like there was an invisible wall there – but it didn't stop him from being a genius of a coach.
"After the Champions League triumph, I felt he was treating me unfairly, but that's how Rafa operated. He did everything so coldly, almost inhumanely, because he saw things as business."
Dudek was sold to Real Madrid by Benitez in 2007, following talks with German club FC Cologne, and the former Poland international admits it was difficult to accept that he was about to blast aside by the Spanish tactician.
He added: "The main interest was from FC Cologne, so I told Benitez I wanted to go there (after being told Benitez wanted me off their wage bill).
"The negotiations started. I was in touch with Cologne regularly and they told me Benitez wouldn't speak to them.
"I was furious with him, absolutely fuming, and in my head I could hear a devilish voice saying 'Punch him in the face – punch him in the face and he'll let you go to Germany'.
"To be completely honest, I genuinely considered punching Rafa in the face. Then the consequences of doing so flashed through my mind. Would he let me go? Or would it just lead to a massive media scandal? Surely I couldn't stay if I gave him a smack?
"I don't know how, but I managed to stop myself."
