Mauricio Pochettino has been warned against taking the Manchester United job, by Gary Neville unless the club's hierarchy promise to back him in the January transfer window and bolster 'the worst back four in the Premier League'.

As reported by Daily Mail Sport, Pochettino is expected to be named as the new Red Devils head coach, with Michael Carrick - who was pictured arriving at Carrington on Thursday morning - set to be sacked later today.

United moved closer to putting Pochettino in charge at Old Trafford after reaching a verbal agreement with the US national team boss on Wednesday. The club then made a formal approach to US Soccer.

Upon Pochettino's expected arrival, he will join a club languishing in the relegation zone - with United 18th in the Premier League with just one win from their opening 10 matches.

United have conceded 19 goals across those 10 games - with only 14th-placed Ipswich Town (20) and bottom side Crystal Palace (24) having conceded more.

And speaking about Pochettino's pending arrival, Neville insists on the Argentine making ultimatums to the board if they want him - starting with improving the defence.

'If I was Mauricio Pochettino now, I would be literally protecting myself up to the high heaven,' he said on The Overlap.

'He'll do that with a pay-off. So do that in your contract. But secondly, he needs two defenders in January. So he's got to insist that he gets two defenders in January. He's got to insist that he gets a minimum budget next summer for the transfer we're not to be able to turn this around. He's got to insist that he gets a budget that follows.

'They have to give it to him or else he shouldn't take the job.'

Expanding further, the former United right back didn't hold back in his criticism of the current defensive options at the club. 

'I mean look the back four that he finished with on Sunday was [Diogo] Dalot left back, [Noussair] Mazraoui right back, Leny Yoro and Ayden Heaven,' he said.

'That is probably the worst back four in the Premier League. I don't know a back four that is worse than that in the Premier League right now if I watch it. That is I can't believe Manchester United have ended up with that back four.'

Pochettino is currently at the US Soccer base outside Atlanta preparing for a CONCACAF Nations League quarter-final double header against Haiti, and is due to speak to the media on Friday.

It’s unclear if he will remain in charge for those games, with United said to be relaxed over the Argentine taking the team. It is possible he could stay for the first leg in Kingston, Jamaica at the weekend and then travel to Manchester.

The second leg is Cincinnati is not until the early hours of Thursday, and Pochettino may even would only take over at United on Friday with a huge game against Liverpool at Anfield 48 hours later.

It’s understood that the US Soccer Federation are ready for this contingency and have a succession plan in place should he leave.

It will cost Pochettino around £7million to buy himself out of his contract with the US Soccer Federation, with United ready to foot the bill.

The cost of bringing in his back-room team, including trusted assistants Jesus Perez and Miguel D’Agostino, will take the cost above £10m.

The 54-year-old only signed a new deal after the World Cup meaning that United could have got him for nothing in the summer.

READ: Man United set to appoint Mauricio Pochettino as head coach: Club make formal approach to US Soccer after agreeing personal terms - with Michael Carrick's exit to be confirmed