The January transfer window is a time of year when teams make a few adjustments to their squad or add depth as they prepare to enter the business end of the season.
However, this winter will be crucial for Manchester United as they look to continue the overhaul of their squad in a bid to keep pace with their Premier League rivals.
Ole Gunnar Solskjaer is expected to dive deep into the transfer market after his side's woeful start to the season that has left them 15 points behind leaders Liverpool after just eight matches.
Solskjaer, who is under huge pressure amid reports Massimiliano Allegri is lined up to replace him, finds himself particularly short of attacking options and lacking the squad depth to compete with Liverpool and Manchester City, as United's current injury crisis has proven in recent weeks.
Central midfield is also an issue of concern while a reliable option at left back is high on the wish list with Luke Shaw struggling to put together a run of games.
It is understood United are keen not to panic buy but there is an acceptance they will need to spend in the coming windows as part of a rebuilding project.
Here, Sportsmail looks at who they are targeting, each player's current situation, why the deal may not work and what they would bring to the team.
Mario Mandzukic
United were keen on signing Mandzukic in the summer but failed to bring him in as a replacement for Romelu Lukaku.
Their interest is still strong though and the Croatian would represent a low-risk option that could seriously improve United's attacking options while offering something different to Marcus Rashford.
It is believed Juventus will be willing to do a deal in January with Mandzukic yet to play in Serie A this season and left out of their Champions League squad.
Thomas Muller
The German is clearly frustrated with his lack of playing time in Munich. The emergence of Serge Gnabry as a regular starter and the arrival of Philippe Coutinho have pushed him out of the picture.
Coutinho has struck up a superb partnership with Robert Lewandowski and that has left Niko Kovac with no option but to bench Muller.
The German's people have made United aware he's available but he ideally wants Champions League football. Unfortunately Solskjaer doesn't look likely to be in a position to offer that any time soon.
James Maddison
United spent big on British talent this summer, welcoming Harry Magurie, Aaron Wan-Bissaka and Dan James. They want to continue that trend by welcoming James Maddison next.
The attacking midfielder would provide the creativity United are lacking and his performances this season have been sensational. He scored in the win over Spurs and netted in front of the Kop last time out.
Leicester do not want to lose their prized asset in January though with Brendan Rodgers refusing to let Maddison go amid the club's push for European football.
Jadon Sancho
Sancho would solve United's problem on the right side for years to come but they must fork out close to £100million to land the England star.
He has excelled for Borussia Dortmund since leaving rivals Manchester City and breaking into the first team and is wanted by almost every European giant.
Dortmund are also against losing him in January and it is thought a lack of Champions League football may steer Sancho to one of United's rivals instead.
Sean Longstaff
The Newcastle midfielder came onto United's radar last season when he burst onto the scene under Rafa Benitez.
He was on the summer shortlist at Old Trafford but a £50m asking price meant a deal was always unlikely, especially given the 21-year-old had only played a handful of times in the Premier League.
Longstaff was also recovering from knee-ligament damage and his form this season has been nowhere near the standard he set last term. The Magpies are still holding out for £50m plus based on what United paid for Wan-Bissaka in the summer.
Eric Dier
The dramatic fall in Nemanja Matic's form has left a huge hole at the base of United's midfield, which has not helped their defence so far this season.
Dier could be the man to fill the gap after being relegated to the bench after falling out of favour under Mauricio Pochettino.
Negotiations with Spurs chief Daniel Levy are always tough though and the uncertainty surrounding Pochettino's future may mean they are unwilling to do business in January.
Moussa Dembele
Sportsmail understands United have sent a scout to watch the French striker three times so far this season.
Dembele has been in fine form and already has six goals from eight appearances in Ligue 1. His previous spell in the Premier League with Fulham would also mean he'd need little time to settle in.
Lyon are in the midst of a crisis at the moment though, suffering their worst start to a season since 1995, and it would take a huge offer to lure away their main man over the winter.
Odsonne Edouard
Edouard is a slightly left field option but could prove to be great value for United at around £30m as an alternative striker.
The Celtic forward has scored nine goals already this season and some of Europe's leading clubs are starting to take note of his maturing performances over the past two years.
United's chances of landing him may be damaged by interest from Napoli and Borussia Dortmund but a deal could be possible if scouts can convince him Old Trafford is the place to be.
Samuel Chukwueze
The Nigeria winger is one of Europe's hot prospects at 20-years-old after bursting onto the scene with Villarreal.
He has drawn comparisons with Arjen Robben due to his dribbling technique and featured regularly for Villarreal throughout the 2018-19 season, where they finished 14th in La Liga and reached the quarter-finals of the Europa League.
Similarly to Valencia's Ferran Torres, another wide man of interest to United, other clubs are interested in Chukwueze and a lack of Champions League football may prove costly in their pursuit.
