Brazilian midfielder Anderson has warned that Manchester United will "lose 30-40%"when Sir Alex Ferguson decides to retire.
Ferguson, 70, has been in charge at Old Trafford since 1986, establishing the club as the dominant force in English football during that time.
But it is generally accepted that he is unlikely to continue in the job for too much longer, and United midfielder Anderson has revealed how much he believes his departure will affect the club.
"Manchester United is Alex Ferguson," the midfielder told Grande Área television in Portugal. "When he leaves, the club will lose 30-40% - so much depends on him.
"He is a father to all the players, a very respected person and when he retires the football world will really feel his loss.
"He always helped me, and I have a great affection for him. He lives for training and always wants to know how his players and their families are."