"In recent months, a shadow has grown inside me that has also changed my way of seeing things," Prandelli said in a letter posted on the club's website.

"I came here to give 100 percent, but as soon as I had the feeling that this was no longer possible, for the good of all I decided to take my step back.

"I am aware that my coaching career can end here, but I have no regrets and I don't want to have any."

Fiorentina said earlier in a statement that the 63-year-old Prandelli had "submitted his resignation to the club management".

"The club, with great regret, accepted the coach's request and understood the reasons, which go beyond football," the Tuscan club said.