United are undefeated in five outings, but the EFL Cup exit to Derby County and tension between manager Jose Mourinho and midfielder Paul Pogba has led to a change in mood behind the scenes at Old Trafford.
West Ham United
West Ham supporters had every reason to fear the worst for their season when Adama Traore's late winner for Wolverhampton Wanderers condemned the club to a fourth successive Premier League defeat before the international break.
Manuel Pellegrini found his side sitting at the bottom of the table and struggling at both ends of the pitch, but a chance to regroup over a two-week period has worked wonders for a club who spent big during the summer transfer window.
A 3-1 victory away at Everton has been backed up by a goalless draw with then-leaders Chelsea and not only has it led to West Ham moving out of the bottom three, it has resulted in renewed optimism at the London Stadium.
The majority of their fanbase will openly acknowledge that they refuse to get carried away with the team's recent progression on the pitch, but it is at least a move in the right direction at a time when the pressure had increased on Pellegrini and his squad.
The fixture list does not get any easier for the East London outfit, with United and Tottenham Hotspur the next two visitors to their home ground, but there is now genuine expectation that positive results can be recorded against either team.
Last Sunday's result against Chelsea could have potentially been better had Marko Arnautovic been fit enough to take his place in the side, although Michail Antonio showed that he is an able deputy by troubling the Blues defence.
Pellegrini will likely be more concerned with ensuring that Fabian Balbuena and Issa Diop continue to forge a partnership at the back having both only moved to England before the start of the campaign, but the signs are now positive that the pair can be an upgrade in the centre of defence.
West Ham will have to be guarded against Man United being keen to respond to all of the negative headlines associated with the club right now, but this could be regarded as a free shot at gaining what had seemed an unlikely result against one of the top-six clubs in the division.
Recent form: LLLLWD
Recent form (all competitions): LWLWDW
A report has suggested that executive vice-chairman Ed Woodward has no plans to part ways with either manager Jose Mourinho or midfielder Paul Pogba, despite the pair's relationship seemingly taking a turn for the worse over the past week.
However, Woodward may be forced to reconsider his stance should United not improve on the pitch, with the club out of the EFL Cup and sitting eight points adrift of leaders Liverpool in the Premier League table.
The midweek penalty-shootout defeat to Derby County will not be regarded as a major setback in the long term, but the performance was again below the level expected by Mourinho and the club's fanbase.
United have now won just four of their eight matches in all competitions this season - despite having only played one of their direct title rivals - and Mourinho must get wins on the board in order to maintain any sort of a challenge for the top-flight crown.
The Portuguese will be aware that he cannot allow any issues with Pogba to linger, but stripping the France international of the vice-captaincy and getting into a confrontation with the player at the club's training ground on Wednesday has only highlighted the tension behind the scenes.
However, Mourinho cannot ignore the form of some of his other key men, with Alexis Sanchez continuing to offer little in the final third and Romelu Lukaku still to find top form after a successful summer with Belgium at the World Cup.
Concerns also remain at the back with only two clean sheets being kept all season, and only a number of chances wasted by Wolves led to United earning a share of the spoils last weekend.
Victory over West Ham this weekend could go a long way to improving matters both on and off the pitch, but defeat may only lead to Mourinho facing a fight to keep hold of his job at Old Trafford.
Recent form: WLLWWD
Recent form (all competitions): LWWWDD
Mourinho is likely to keep Sanchez in the starting lineup, despite the Chilean being withdrawn early in the second half against Wolves last weekend.
Pellegrini is likely to name the majority of the team which began the league fixture against Chelsea, with the one selection issue revolving around Arnautovic.
The Austria international could be back in contention after a knee problem, but Pellegrini must decide whether to keep faith in Antonio at the head of a three-man attack also involving Felipe Anderson and Andriy Yarmolenko.
Robert Snodgrass has also put himself in Pellegrini's thoughts with two goals in the 8-0 demolition of Macclesfield Town on Wednesday night.
West Ham United possible starting lineup:
Fabianski; Zabaleta, Diop, Balbuena, Masuaku; Noble, Rice, Obiang; Anderson, Yarmolenko, Arnautovic
Manchester United possible starting lineup:
De Gea; Valencia, Smalling, Lindelof, Shaw; Matic, Pogba; Sanchez, Lingard, Rashford; Lukaku
Head To Head
Saturday's clash will represent the 140th competitive meeting between the two clubs, with Man United registering 65 victories in comparison to 43 wins for West Ham.
The Hammers have a dismal recent record against the Red Devils, with just two wins and seven draws coming from the last 19 encounters in all competitions.
However, West Ham were able to register a goalless draw in last season's corresponding fixture in May.
We say: West Ham United 1-2 Manchester United
West Ham will be on a high after their recent results - and having kept successive clean sheets at the London Stadium - but United need a response to put themselves back into the title picture and we feel that the North-West giants will edge to victory in England's capital.