Diego Simeone believes Diego Costa is the most important player to feature for Atletico Madrid in recent years.
Costa returned to Atletico action this month, becoming eligible to play following a return transfer from Chelsea that was announced in September.
The Spain international laid on an assist for Yannick Carrasco as Atletico beat Lleida 3-0 on Tuesday to wrap up a 7-0 aggregate triumph in the Copa del Rey.
It means he has been involved in three goals in three games since making his return, having found the net twice already for the Rojiblancos.
Costa helped fire Atletico to LaLiga glory and the first of two Champions League finals in three seasons in 2013-14.