Ruben Amorim said he feared his Manchester United side were forgetting their responsibilities as players at one of the world's major clubs, while casting doubt on his own future with the Red Devils following a 2-0 loss at home to West Ham on Sunday.
Just three days after United reached the Europa League final, they were brought back down to earth by another lowly side in the Hammers, with the London club recording their first top-flight win at Old Trafford since 2007.
Tomas Soucek and Jarrod Bowen scored the visitors' goals as United, once the undisputed kings of English football suffered a 17th defeat in 36 league games so far this season, with nine of those reverses taking place in front of their own fans.
This latest lacklustre display angered Amorim, who has already given his team several public dressing downs since replacing the sacked Erik ten Hag as United manager in November.
"For me the biggest concern is that feeling that 'it’s OK', and 'we cannot change our position so much so it's OK'," Amorim said after Sunday's latest loss.
"That is the biggest problem in our club in this moment because we are losing the feeling of we are a massive club and it's the end of the world to lose a game at home. I think that is the biggest concern in our club."
The 40-year-old Portuguese coach, previously in charge of Sporting Lisbon, added it was the the most dangerous feeling that you have in a big club," with United having not won the Premier League title since celebrated manager Alex Ferguson retired in 2013.
'EMBARRASSED'
Amorim, asked how it felt to see his side a lowly 16th in the Premier League table with two matches remaining, replied: "How a manager of Manchester United is supposed to feel in that position –- embarrassed and it's hard to accept."
And he insisted a Europa League final with fellow English strugglers Tottenham in Bilbao on May 31 could not distract from United's domestic woes.
"Everybody is thinking about the final," said Amorim. "The final is not an issue in this moment in our club. We have bigger things to think (about)and we have to change a lot of things in the end of the season."
Amorim, who has overseen just six league wins since succeeding Ten Hag, reiterated United "need to change a lot of things during the summer".
And he was adamant a key issue was his own performance, with United now on a seven-game winless run in the league ahead of next week's match away to Chelsea.
"I don't want to talk about players," Amorim said. "I'm talking about myself and the culture in the club and the culture in the team.
"We need to change that and we need to be really strong in the summer and to be brave because we will not have a next season like this. If we start like this, or if the feeling is still here, we should give the space to different persons."
For the Hammers, victory ended an eight-game wait for a win.
"Very pleasing result, especially in the context of what we've been through," said West Ham manager Graham Potter. "It's been a tough couple of months because results have been not what we've wanted.
"Performances haven't been as bad, but you know what it's like. If you don't get the results, you have to suffer in the Premier League and that's what we had to do."