Jose Mourinho accused some of Manchester United's under-performing players of lacking "heart" against Crystal Palace - an attribute the manager believes is the bare minimum for his stuttering side.
Boos echoed around Old Trafford on Saturday afternoon as the hosts floundered against struggling Palace, who were unfortunate not to return south with more than a 0-0 draw.
United are now 14 points behind table-topping Manchester City - the same gap there is to rock-bottom Huddersfield - and, perhaps more worryingly, let this opportunity to bolster their top-four chances pass them by.
Mourinho had talked up those hopes ahead of the match and did not hold back after this "bad result" against Palace.
"Not enough intensity, not enough desire," the United boss said.
"So, I think we played a game like 'one more game' and I don't think the game is 'one more game'. I think it is a game we really need to win.
"If we played with the same philosophy against Young Boys (in the Champions League on Tuesday) then we don't win and then we have to go to Valencia to win the game in Valencia.
"So, there are matches that are special matches and that not just one more - and this one was not just one more.
"It was the first of eight Premier League games until the end of December and was a game we need to win, and my feeling is that there was not enough from the heart.
"You must play with brain, we must play also with heart and I think (there was) not enough heart."
Mourinho did not name names after the 0-0 draw, but appeared to call into question the character of Jesse Lingard, Luke Shaw, Anthony Martial and Marcus Rashford in an interview aired before the game.
Of that quartet, only Lingard and Martial started on Saturday, when the decision to replace ineffective Paul Pogba with Alexis Sanchez was met by cheers from some at Old Trafford.
It was a maddening return from the international break for Mourinho but the United manager does not believe some of his players will feel that frustration.
"There are people that will have a bad dinner (this evening)," the Portuguese said.
"There is people that will enjoy a nice dinner and there will even be people that maybe will party. I think that's the way it is."
Put to Mourinho that it is surely the bare minimum to play with heart, Mourinho said: "I agree, I agree.
"What's the solution? You cannot change players' natures dramatically.
"The solution is that probably I have to make certain choices based on heart, and then probably I will blame myself because I will think heart is not enough and I am missing here some quality."