Panathinaikos manager Jesualdo Ferreira has resigned following a run of just two wins in 14 competitive matches.
The Athens club, who sit sixth in the Greek Super League, have put Under-20 coach Juan Ramon Roch in charge of first-team affairs ahead of this weekend's league game against PAOK.
"Panathinaikos has entered a critical period and we need everyone who can help," said Rocha.
"I am always available to the Association and for that reason I come to assist in this difficult time."
Panathinaikos look likely to be eliminated from the Europa League at the group stage, having taken just two points from their first four matches.
