Key move needed if the Red Devils are to complete an important transfer.

Manchester United are trying to bring in a left-back before Tuesday’s transfer deadline, but one crucial development is required for that to happen.

The Red Devils are light in that area, with Luke Shaw currently their only recognised senior option on the left side of the defence.

Patrick Dorgu has been considered as cover, but the Dane has not played in that position throughout the season after being moved further up the pitch by manager Michael Carrick following his arrival in charge at Old Trafford.

A report from the Daily Mail said United had a contingency plan if they failed to sign a left-back before the transfer window closes. That plan included testing Lisandro Martinez or new midfielder Carlos Baleba as emergency alternatives, or making use of the versatility of Noussair Mazraoui and Diogo Dalot to provide cover for Shaw.

The other possibility would be for academy graduate Harry Amass to remain at the club, even though he is not currently part of the first-team plans amid discussions with Burnley over a possible move.

Now, Sky Sports has reported that there is one major step that must be taken if Carrick is to secure a left-back signing this summer.

That step is Joshua Zirkzee leaving the club, either on loan or on a permanent transfer, before Tuesday’s deadline.

The Dutch striker has slipped to the fringes at Old Trafford, sitting behind Benjamin Sesko, Matheus Cunha and Bryan Mbeumo in the pecking order for the lone centre-forward role in Carrick’s 4-2-3-1 system.

As a result, he has attracted interest from Juventus and Fiorentina, both of whom were keen on taking the former Bologna player back to Serie A.

Juventus had moved forward in talks over a loan deal for him before switching their focus to Newcastle’s Nick Woltemade, who has travelled to Turin for a medical.

Fiorentina were also said to be interested before agreeing a deal with Everton to sign Beto, while the Toffees are looking at former Arsenal forward Folarin Balogun of Monaco as his replacement.

If Zirkzee leaves United before the window closes, it would create room in the club’s wage structure to allow a left-back signing to go through.

That said, the situation could become difficult if another interested club does not move quickly to firm up its pursuit.

United have been linked with Newcastle’s Lewis Hall, Barcelona’s Alejandro Balde and Aston Villa full-back Ian Maatsen as they continue their search for a left-sided defender.