Atletico Madrid have confirmed that Quique Sanchez Flores is suffering from swine flu.
Flores was only appointed Atletico boss in late October following the dismissal of Abel Resino.
They have continued to struggle in recent weeks and are currently languishing in the bottom three of the Primera Liga.
Flores will not be able to help his players prepare for their upcoming game against Deportivo La Coruna until he has fully recovered, with assistant boss Fran Escriba temporarily taking charge of training.
"Tests have confirmed that the coach is suffering from the flu," Atletico reported in a statement on the club's official website.
"The manager is following the appropriate treatment and a good recovery is predicted."