Fonseca was dumped by Milan on Monday morning and replaced by former Porto coach Sergio Conceicao.
It's since emerged that Fonseca learned of his dismissal on Sunday by a simple text message sent by the club's American owner Gerry Cardinale, reports SkySport24.
Fonseca announced his dismissal in the early hours of Monday morning to local reporters - a good eight hours before Milan announced their decision
Upon learning of the Portuguese's treatment, the Curva Sud released a statement declaring: "A management team can no longer be credible after having spent an entire summer boasting of being firmly convinced by the Fonseca project.
"You have found your scapegoat, who, if he is not up to the situation from a sporting point of view, has shown himself to be much more serious and courageous than you, who abandoned him in August."