Ruben Amorim admits Manchester United are in a relegation battle

They have lost four successive games in all competitions and five of their last six league games, including their last three at home.

Asked if he sensed United were being drawn into a relegation battle, Amorim told Sky Sports: "That is really clear and we have to fight."

The Portuguese added in his post-match press conference: "We have to acknowledge our position...we have to win games and focus on surviving."

Asked if it was embarrassing as United manager to be talking about relegation, Amorim, who has been in charge for 11 games in all competitions, said: "Yes - it's also my fault in this moment, because I think the team is not improved, I think (it) is a little bit lost in this moment.

"It's a little bit embarrassing to be a Manchester United coach and lose a lot of games. But we have to cope with that, difficult moments in the life of everybody. It's a hard moment."

He added: "I don't like to arrive here and make excuses. I think people are tired of excuses in this club. And I think sometimes I talk about relegation because of that - I think our club needs a shock and we have to understand that.

"It's a very difficult moment and we have to fight for the next game and to implement the idea to win games and to have also performance, because I think we are losing some things from the last games."

United were dismal in a first half that saw Newcastle score through headers from Alexander Isak in the fourth minute and Joelinton in the 19th.

Amorim made a tactical adjustment in the 33rd minute as Joshua Zirkzee came off to an ironic cheer from the crowd, replaced by Kobbie Mainoo.

Zirkzee initially went down the tunnel before returning, and Amorim said: "He wanted to be (in dressing room) and then he returned in the second half.

"It was a very difficult moment and he is a human being, but then he felt the support of the fans in the end so everything is OK."

Newcastle rose to fifth with their fifth win on the bounce, fourth in the league, and first league victory at United since 2013.

Boss Eddie Howe said: "We know the hurt this fixture has had for us historically, it wasn't lost on us. We didn't necessarily use that with the players, but psychologically that was a big step forward for us today.

While Newcastle go to Tottenham on Saturday, United's next match is a trip on Sunday to league leaders Liverpool.

Ruben Amorim admitted Manchester United's dismal run of form is making it harder for him to sell his players on his tactical model.

Monday's 2-0 home loss to Newcastle saw United suffer five league defeats in the same calendar month for the first time since September 1962, and a fourth straight reverse in all competitions means the Red Devils have lost six of their last eight.

Amorim is yet to do anything to arrest the alarming slide which led to Erik ten Hag's dismissal in October.

Much has been said about Amorim's 3-4-3 system and the difficulties United's squad have had in adapting, but the Portuguese is determined to press on.

"Of course I didn't choose the players specifically for these positions but that I already knew," he said.

"I have to sell my idea. If I am going to change all the time it is going to be even worse.

"But I understand they have a lot of difficulties because they spend two years playing one way and then they are playing another and with a lot of losses, it's really tough on them and you can feel it during the game.

"Even (against Newcastle) when we are near to scoring it's more from (Newcastle mistakes) than the organisation and you can feel it but I have to sell my idea, I don't have another one."

Amorim did not have the benefit of a pre-season to implement such a major change to United's tactical model, and admitted that is having a significant impact.

He said: "I think we showed some improvements in the first games, especially against (Manchester) City and Tottenham and even Arsenal in the first moments but we are losing that because of a lack of training and a lack of belief after so many losses.

"Some difficult moments when you suffer some goals at the beginning of the game, it's then really hard during all the games so they are really tough moments for everybody.

"I think the players are losing everything, the small things that we try to work on in training.

"After one goal they lose everything because we don't have the base, we don't have time to build the base to cope with the difficult moments so it's really hard in this moment."