A dull and drab encounter was brought into life in the 93rd minute, as Marcus Rashford tapped home from an Edinson Cavani assist, and a wonderfully waited pre-assist from the forgotten man Anthony Martial.
Martial was superb coming off the bench, showing sublime creativity through his excellent passing and dribbling, and invoking some much needed fear into the West Ham defenders.
Having four forwards on the pitch at the end of the game, was it a stroke of genius from Ralf Rangnick? Or a slice of luck? Either way, United need not care, as they (albeit temporarily) move into fourth.
The game started off well for Man United, with them clearly dictating play and possession, but lacking any serious incision to carve West Ham apart, who from early on were clearly primed and ready to hit on the break.
They were very quiet in the first half, largely camped inside their own half, but as they moved on into the second half, they clearly grew into the game, with some quick, penetrative counter-attacks, but they consistently lacked the final pass, shown by their solitary shot on target.
However United weren't much better for large amounts of the game, and it was clear to see players were tiring, and frustration was growing amongst the crowd and players alike around the hour mark.
Players such as Bruno Fernandes and Alex Telles were shooting wildly from long range, and it was clear that United were becoming desperate and wasteful, as they were in need for some ingenious creativity.
Martial coming on was a massive factor in United winning the game, with his accurate passing, and precise and coherent dribbling allowing the Reds to increase their ball retention higher up the pitch, and eventually work an opening, with an incisive, defence-splitting run from the man himself, and an accurate pass across the fact of goal from Cavani, allowing Rashford to tap in the winner.
It will certainly do Rashford's confidence a lot of good, as he has now grabbed 2 in 2 off the bench, and could Martial look to have played himself back into Ralf's plans, despite him looking for a move elsewhere? He certainly looks United's most creative and complete forward, and a front three of Jadon Sancho, Martial and Cristiano Ronaldo could be deadly with options such as Rashford and Anthony Elanga and Cavani to come off the bench.
Mason Greenwood was greedy for large parts of the game, as despite completing some nice dribbles, he consistently lacked the final pass.
It was the same story for Fernandes, and Scott McTominay who had a really poor game as the six, losing the ball countless times high up the pitch, whereas Fred was excellent, completing his destroyer role in the midfield to great effect, and keeping the game simple with some nice short and quick passing, paired up with his ever-present tenacity and tackling.
Rangnick took a gamble by making the substitutions so late, but it paid off, with the three substitutes linking up fluently, coherently and ruthlessly, to break West Ham hearts, and seal a much needed, and perhaps undeserved, 1-0 victory.
Manchester United Player Ratings;
De Gea - 6 - Had nothing to do.
Maguire - 7 - Played well, strong in the tackle, and sprayed some accurate long range balls.
Varane - 7- Excellent, calm and composed in the tackle, showed good strength in the tackle, and never put a foot wrong.
Dalot - 7 - Positive and direct running forward, whipped in some nice crosses, and looked solid defensively.
Telles - 5 - Not his best game, had a wild, unnecessary shot in the second half, and did not really get forward as much as he usually does.
McTominay - 4 - Poor passing, didn't show for the ball, which is vital when playing as a 6, lacked discipline. Needs to play as an 8.
Fred - 7 - Excellent tenacity, passing and tackling.
Fernandes - 5 - Wasteful in possession by shooting from distance, and passing was evidently off.
Ronaldo - 6 - The graveyard shift, had no service.
Greenwood - 5 - Needlessly cut in in the first half when he should have shot with his right foot, lacks creativity, and looks a player bereft of confidence.
Elanga - 6 - Tidy when he had the ball, but he was largely invisible.
Martial, Rashford Cavani were all 7's off the bench, for reasons mentioned above.
West Ham United Player Ratings;
Areola - 6 - Decent stop from Fred, but a largely quiet game.
Coufal - 5 - Booked, which encompassed a largely cynical performance from him.
Dawson - 6 - Looked solid, accurate passing and put in a good shift.
Zouma - 7 - Looked good, kept Ronaldo quiet, and tackled and passed well.
Cresswell - 7 - Got up and down the flank well, and solid defensively.
Soucek - 6 - Quiet game, but a battling performance.
Rice - 8 - Superb performance, completed some excellent dribbles, screened the back four expertly and didn’t put a foot wrong.
Lanzini - 5 - Largely invisible
Fornals - 6 - Workman-like performance, putting in a good shift defensively.
Bowen - 7 - Looked threatening with some quick feet and tidy passes, but lacked composure in his shooting.
Antonio - 6 - Attempted to occupy both centre-backs but was largely quiet and struggled due to lack of service.