Paul Scholes has warned Manchester United they risk suffering an unfathomable relegation from the Premier League in the near future if they do not improve the squad this summer and sign at least five players for Ruben Amorim.

The Red Devils – who currently sit 13th in the league with 24 games played – are on course for their worst-ever Premier League season and have won just four league games since the Portuguese boss' arrival in November.

The club did dip into the January transfer window amidst their struggles, as they signed wing-back Patrick Dorgu from Lecce for an initial £25m and central defender Ayden Heaven from Arsenal, although the teenager has made just one senior appearance in his career thus far.

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United's poor form has continued as they suffered their seventh home defeat of the season in a 2-0 loss to Crystal Palace earlier this month, while a last-minute offside goal saw them fortunately scrape past Ruud van Nistelrooy's relegation-threatened Leicester City in the FA Cup fourth round on Friday night – which set up a tie with Fulham.

Scholes lamented the lack of spine in United's squad, admitting that a total of five players must be signed to rectify the situation, otherwise relegation to the Championship could become a very real possibility down the line.

"There are a few things that are concerning. There's a lot of stuff he (Ruben Amorim) needs to do, we all know that, especially in transfer windows, but I don't see a core of players," he told The Overlap Fan Debate, brought to you by Sky Bet.

"When you look at teams, you look right down the spine of a team. Liverpool: great goalkeeper, great centre-half, forwards, midfielders, whatever. I don't think United have any of that in any position. I think a new goalkeeper is needed, possibly two centre halves, two centre-midfield players, and two centre-forwards.

"Alright, I'll go for one centre midfielders and one centre-forward, but with a bit of stature, a bit of quality, and really create a spine. When you've got that spine right, then you can add bits to it.

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"That spine, that core, is so important. If they don't get that right this summer, this might sound ridiculous, but the form since this manager is in, they could be looking at relegation. I'm telling you, it's been so bad."

United travel to Tottenham Hotspur in their next league outing on Sunday, and a defeat in north London would see Amorim's side drop to 14th with Spurs leapfrogging them, while West Ham and Everton are also hot on their tail. As things stand, though, 12 points separates United from the relegation zone.