Paul Merson has criticised Manchester United’s decision to sign Andrey Santos and says the Red Devils will be in the relegation zone come December.

Brazilian midfielder Santos has made an inauspicious start to his United career following a £50m move from Chelsea over the summer.

The 22-year-old has started less than half of Manchester United’s games so far this season and struggled to make an impact when he has featured.

Santos is certainly not the only player at Old Trafford under-performing, with Michael Carrick’s side only out of the relegation zone on goal difference following their worst start to the season since the 1980s.

United’s next five league games are against Aston Villa, Liverpool, Brentford, Newcastle United and Coventry City, and Merson believes they will be sitting in the drop zone by the time they face Frank Lampard’s side in early December.

‘Manchester United play Coventry on the 5th of December and I’d be shocked if they’re not in the bottom three by then,’ Merson told Sky Sports.

‘That’ll be about a third of the season gone then. They might go and get a big result next weekend, Aston Villa looked beatable the other day.

‘I don’t see them getting relegated, absolutely not. But this is not Manchester United and there’s no quick fix, they got it all wrong upstairs.

‘The first window, they went for the forward line but it wasn’t good enough. Matheus Cunha, Bryan Mbeumo, Benjamin Sesko, they’re nice players but they’re not 20-25 goal-a-season players.

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‘You’ve got to be a seven, seven and a half out of 10 every week at Manchester United. But they’re a four one week, a nine the next. You can play for Wolves or Brentford and do that, no disrespect.

‘The day you’re a nine you win the match and everyone’s pleased. When you’re a four, people say that’s just the way it is.’

Merson believes a weak and unbalanced midfield is one of Manchester United’s biggest issues, questioning the decision to sign Santos from Chelsea.

‘The midfield they bought – I’d love to see what they saw paying £50m for Andre Santos,’ Merson added. ‘Tell me what you saw that I didn’t when I was watching him every week at Chelsea.

‘Youri Tielemans, he’s a good player but there’s no legs around him in the team. He had legs around him when he was playing at Villa.

‘How do I know there’s no balance in the midfield they’ve bought and they don’t? Two years ago, you’re looking at Casemiro and saying he’s a million miles off it. Now you look at it and think they miss him.

‘And now they say they’ll work on the defence in the next window. It’s madness – you can’t build a house on a puddle. You just can’t. Why not start with the defence first and then go from there?

‘They say they’re going to go and outscore teams but they haven’t bought players who score enough goals.

‘I don’t know where everyone expects them to be. I didn’t expect them to beat Como, I didn’t expect them to beat Bournemouth, I didn’t expect them to beat Chelsea and I don’t expect them to beat Villa.’

Before Manchester United resume their faltering Premier League campaign, they face Italian side Roma in the Champions League.

Carrick’s side are just 20th in the Champions League while Roma are 14th and up to third in Serie A following an impressive run.