As the Scottish tactician gets set to notch up 25 years in charge of the Red Devils, Chicharito has spoken how no-one else is like him and how his enthusiasm and will to win are among many great attributes he possesses.
"He is completely different," Hernandez told Inside United. "You can't compare him to anybody else.
"What has impressed me most about him, and this is something I have noticed from the first day I met him, is that he is a very simple person.
"You can talk about all the things he has won and all the years he's been in charge but you wouldn't know it if you watched him on the bench.
"Every game looks like it is his first. He is so excited. So enthusiastic. He wants to win so much.
"That is the key. He will never get bored of winning and he enjoys what he does."
He added: "He is just an unbelievable person. He recognises that first you are a human being and then you are a football player.
"Manchester United is the best club in the world so you would always want to come here, but to be part of one of Sir Alex's teams was a huge factor.
"I hope he stays on for a few more years and then, when it comes time for me to retire, I will be proud to say I was one of Sir Alex's players."