The Argentine defender’s move to Liverpool was stopped by the Manchester United boss.
Heinze told the Daily Mail: “It has been complicated. I am convinced my move to Liverpool would have worked out and I believe I had a case and needed to defend my rights.
“I am grateful for what Rafa Benitez said and tried to do.
“I didn’t want more controversy with Sir Alex Ferguson.
“It is logical now for me to make this jump.
“I always said I wanted to leave for one of the big clubs in Europe and Real are one of those.”