Manchester United have been in fine form of late and one of the factors behind that is the team’s incredibly well-balanced midfield.

After flirting with a 4-2-3-1 system earlier in the season, Jose Mourinho now seems to have found the perfect formula in midfield with Michael Carrick sitting just behind Ander Herrera and Paul Pogba in the centre.

A wonderful trio with little in reserve

All three seem to complement each other perfectly, with Pogba and Herrera’s energy making up for Carrick’s lack of pace and mobility. However, the veteran Englishman’s intelligence and defensive-minded style has allowed that duo, Pogba especially, to thrive in a more attacking role.

However, United’s midfield three doesn’t have a great amount of cover. Morgan Schneiderlin and Bastian Schweinsteiger might have been considered as viable alternatives to Herrera and Carrick respectively not too long ago. However, the former looks likely to leave in the next few weeks while the ex-Germany captain's future remains uncertain.

Dutch pair Daley Blind and Timothy Fosu-Mensah are other potential midfield options for United, but neither have featured heavily there since Mourinho’s arrival for contrasting reasons. The former has played at left-back and centre-back under the Portuguese, while 18-year-old Fosu-Mensah has only been sporadically involved this term in various positions.

That leaves Marouane Fellaini as the main alternative to the favoured three in midfield and, while the 29-year-old is well trusted by his manager and regularly demonstrates an admirable work ethic, the drop in quality from any of Carrick, Herrera or Pogba to him is huge.

Depth over quality in short-term for United

It is peculiar then, that United have been more heavily linked with signing a central defender rather than a midfielder in the upcoming transfer window. Some reports have suggested a deal for Victor Lindelof of Benfica – who seemed almost certain to join next month not so long ago – has been cancelled, but a host of other defenders have also been linked with a move to Old Trafford.

Lindelof’s move is said to have collapsed because of just how pleased Mourinho has been with Phil Jones and Marcos Rojo’s form in defence, per the BBC . That duo looked like mere backup options at the start of the season but have since forged a partnership seemingly stronger than any other at the club in recent times.

Jones and Rojo may not be the long-term option at centre-back for United, but with Chris Smalling and Eric Bailly, as well as the aforementioned Blind, available in the middle of the defence for Mourinho – the Red Devils do at least have some sense of strength in depth at the heart of their backline.

The quality which United possess at the back might not be quite as strong as Mourinho would like if his side are to push for Premier League titles in future seasons, but it is depth which the Red Devils require – in all areas of the field – between now and the end of the season.

Successful season still possible for Red Devils

A domestic title looks out of reach this term, but United are still competing on four fronts and could yet end the current campaign in successful fashion, despite sitting sixth in the League at present.

Only Hull City stand in the way of an EFL Cup final spot, while players and fans alike will surely hope to retain the FA Cup come May. Champions League qualification for next season can still be earned with a successful Europa League campaign or a top-four finish in the league – although Mourinho will surely want both.

But if United are to remain in contention in all of those competitions in the final weeks of the season, they will likely need another midfielder. Pogba, Herrera and Carrick won’t be able to play every game – especially the ageing latter – and Fellaini, although undeserving of some negative fan support shown towards him, would worsen both the quality and balance of the midfield by replacing any one of that trio.

Whether it be a short-term stop-gap or a potential successor to 35-year-old Carrick, United should increase their numbers in midfield in January to improve their chances of success this season.