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 this season to sit 16th.

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.

"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."

The 40-year-old Portuguese coach, previously in charge of Sporting Lisbon, added it was "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 so low in the Premier League, replied: "How a manager of Manchester United supposed to feel in that position –- embarrassed and it's hard to accept."

And he said a Europa League final with fellow English strugglers Tottenham in Bilbao on May 21 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, said United "need to change a lot of things during the summer" and questioned his own future if he can't oversee a significant improvement.

"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 not been 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."