Mancini says he's been following Silva since he was in charge of Inter Milan.
"I am just happy to be working with him," he revealed.
"I remember when I first saw him playing for Valencia against Inter in the Champions League. He was only young then but you could see his potential. He was astonishing. He has improved a lot in the last two years and now he is one of the best players in Europe, if not the world. He could play for Real Madrid or Barcelona, but I am glad to say he plays for Manchester City."