The Magpies look destined for relegation to the Championship this season.
The Spaniard is currently in charge at St James’ Park until the end of the season, having replaced Steve McClaren in the hot seat.
So far he has not been able to turn around their fortunes, with Saturday’s loss to Southampton seeing them now sit six points from safety in 19th place.
He has arguably found the situation more dire than he anticipated, and it seems that the one thing that has left him particularly shocked is the mental fragility in his side, reports the Telegraph.
Indeed, according to the report, he has questioned certain players in the squad over their attitude, asking why they cannot perform in matches as they do in training.
Benitez is not the only one to have questioned the desire in the squad either, with Jamaal Lascelles having also called out his teammates on the matter.
The defender was pictured questioning his teammates during the loss to the Saints, and later led a dressing room inquest following the defeat, according to the Chronicle.