Ruben Amorim conceded Manchester United are getting dragged into a Premier League relegation battle following their defeat by Newcastle United.

The Red Devils suffered their fourth loss in five league games, as first-half goals from Alexander Isak and Joelinton gave the Magpies a 2-0 victory at Old Trafford on Monday. 

Amorim is already under pressure, having overseen five defeats in his first eight league matches in charge; the worst record for a United manager in 103 years.

His side lost six games in December, their most in a single month since September 1930 (seven).

Amorim acknowledged the club are enduring "one of the more difficult moments in history", but insisted he would not change his approach.

"That is really clear [United are being dragged into a relegation battle], so we have to fight," he told Sky Sports.

"It is a really difficult moment - one of the more difficult moments in the history of Manchester United - and we have to address it with honesty.

"It was really hard on us. They were the better team and they started very strong. The players suffered a lot on the pitch.

"It was very hard for us to turn it around after we conceded the first goal because of the results before, and we didn't have the positioning to cope with the difficult moments.

"Maybe [you change approach], or you continue with your idea, and they have to change the coach. It is a choice that everyone has to make in football.

"If I think this is the best thing for the team, I will continue to pass my message."

The Red Devils have now lost three consecutive home league games for the first time since February 1979, while they have lost three consecutive Premier League games within the same season for the first time since December 2015 under Louis van Gaal.

United will end New Year’s Eve in 14th place in the Premier League, their lowest position at the turn of the year in the league since 1989, when they ended that year in 15th, eventually finishing 13th.

Amorim also explained his decision to substitute Joshua Zirkzee after just 33 minutes against Newcastle, with the forward replaced by midfielder Kobbie Mainoo.

"You have to think about the team and the player, but the player is suffering," he added. "I thought the team was suffering, and we needed another midfielder to have more ball.

"It was really tough for me to do that, but I've spoken to Josh as it was important to express the message. For the team, it was important for Josh to go out.

"I know that Josh is a really good guy. When he went to the tunnel, I can understand that some guys can be in a bad way, but he is a really good lad.

"It is life, and we will support Josh and continue. Newcastle were better than Manchester United, they weren't better than Josh."