Mauricio Pochettino says Chelsea's 4-1 defeat away at Newcastle was "the worst performance of the season".
The Argentine fumed at a calamitous second-half display, saying he was "very, very angry" because his team lacked competitiveness.
Newcastle won comfortably despite having 13 players out and three goalkeepers on the bench.
After the match, Pochettino raged at his players, having watched on from the directors' box.
"Disappointed with our performance, it was our worst game of the season. It's about to blame ourselves," he said.
"It was so easy the way that we conceded. We were soft in every single challenge; we should have shown we were playing for something important.
"That is why it made me angry and disappointed. We need to learn even if we talk about being a young team. These types of games make me very, very, very, very angry because they are about showing more personality and character.
"Okay, we are young but we can not miss this type of opportunity to show our best. We can not come from Tottenham, Man City, [where] around the world people praised Chelsea and then… we stop one step before and don't make the effort in the right moment -- we need to be more solid in this area.
"It is about showing more strength in our mental game and being ready to compete. This is not the same as simply playing football. I can play football, you can play football but to compete? I want to be ready to compete but today we didn't."
The defeat was sparked by a disaster 90 seconds when lax marking led to a Jamaal Lascelles headed goal before Thiago Silva's mistake allowed Joelinton to extend the lead.
Anthony Gordon rounded off the scoring with both Alexander Isak and Raheem Sterling netting in the first half.
He refused to blame Silva for his error but criticised Reecen James for his red card after he pulled back Gordon on the break. .
"Disappointed... look, this type of thing happens in football. Of course, disappointed of course because we should finish with a player [on the pitch] but it happens and we need to accept it."
Pochettino also apportioned blame on himself and his coaching staff, adding: "The big teams perform every week or every three days in this way. That is a thing we need to set in the team."
