A calamitous error by David De Gea condemned Manchester United to a 1-0 loss against West Ham at the London Stadium which leaves their top-four hopes in jeopardy
Said Benrahma's tame, long-range effort in the first half should have been a routine save for the goalkeeper but, despite getting a hand to it, he was unable to stop it from bobbling over the line
Manchester United, beaten 1-0 by Brighton last time out and only a point ahead of fifth-placed Liverpool, appeared in control of the game before De Gea's mistake but could ultimately have lost by a greater margin, with the hosts dominating much of the second half as they took a huge step towards Premier League survival
David Moyes' side created numerous chances and were also denied what looked a clear penalty on the stroke of half-time when Victor Lindelof's handball went unnoticed by on-pitch referee Peter Bankes and VAR Stuart Attwell decided not to intervene
The decision ensured Erik ten Hag's side remained in the game but West Ham withstood late pressure to claim a deserved victory which was Moyes' first over Manchester United since his spell in charge of the club
 The result sees the Hammers move to 37 points, easing their relegation fears in 15th
Manchester United, meanwhile, remain in fourth place and, while they still have a game in hand on Liverpool, their stuttering form has thrown the top-four race open
Manchester United started the game positively but lacked accuracy with their shooting as Bruno Fernandes and Antony dragged efforts wide of Lukasz Fabianski's right-hand post
Christian Eriksen spurned another chance, shooting over the bar when left in space to meet Antony's pull-back, while Marcus Rashford struck another angled effort against the outside of the post
West Ham only threatened sporadically in the opening stages and had De Gea to thank for their opener, the Spaniard burying his head in the turf after allowing Benrahma's tame strike, after Luke Shaw had lost possession, to trickle into the net
It was the under-fire goalkeeper's fourth error leading to an opposition goal in all competitions this season - the joint-most by any Premier League player along with Tottenham's Hugo Lloris
Man Utd tried to muster a quick response but Antony's deflected long-range effort hit the wrong side of the post, and they were fortunate not to concede a penalty just before the break when Victor Lindelof's handball inexplicably went unpunished
The momentum remained with West Ham, though, with the hosts pinning Manchester United back and creating a succession of chances in the second half
Declan Rice, outstanding on his return to the side following illness, was at the heart of most of it, while De Gea continued to look nervous in the Manchester United goal, the Spaniard fortunate when Michail Antonio was adjudged to have fouled him before poking the ball over the line following a corner
Tomas Soucek also had the ball in the net, only for his header to be correctly ruled out for offside
 The Czech midfielder also struck the side netting with one effort, while Lucas Paqueta fired narrowly wide on another occasion as they continued to push for a second
Manchester United did show some improvement in the latter stages, finally managing to subject West Ham to an extended period of pressure, but the hosts defended resolutely, with Fabianski also saving smartly from Rashford and substitute Anthony Martial
The home team left the pitch amid a party atmosphere at the London Stadium, while Manchester United's dejected players trudged off knowing the top-four battle is far from over
"Huge step [towards safety]
 To beat Manchester United in a run-in is a huge step
 Getting three points against whoever is huge, but against Manchester United is massive for us
"It was probably well deserved given how well we performed
 The players showed great character, great spirit
 We had to dig deep at times but we also had great moments and played a lot more like the West Ham we've seen in the last couple of years
"It's a great result going into the semi-final of a European competition and the positive we will take from it, playing against as good a side as Man Utd, we knew were up against it
"Now we've got another big challenge in midweek and it's one we will looking forward to
" "Just add it to the other ones which have happened to us in recent games
 We hope that somewhere along the line in the coming games we get a penalty kick or something that goes in our favour
"We want him to stay and we want him to extend his contract
"He has the most clean sheets in the Premier League
 We would not be here in this position without him
 He has my belief
 No concerns
"That happens, but I think as a team you have to deal with it, you have to show character and be resilient and bounce back
"I think we started well
 We dictated the game
 We created chances
 But we didn't take them
 And then, one mistake
 But even then, until half time, I think we played a decent game
"In three days, twice an individual mistake leads to us losing games
 I'm disappointed but it is what it is
"Now we have one week [off]
 It's the first time since Christmas that those players have a full week
 We have to reset, reload, to get the energy back and then keep going
"West Ham host AZ Alkmaar in the first leg of their Europa Conference League semi-final on Thursday
 Kick-off 8pm
 They then resume their relegation battle at Brentford on Sunday May 14 with kick-off at 2pm
Manchester United have four games remaining to secure a place in the top four
 They host Wolves on Saturday at 3pm, then head to Bournemouth on May 20 before finishing with two home games against Chelsea and Fulham
May 11:  (H) - Europa Conference League, kick-off 8pmMay 14:  (A) - Premier League, kick-off 2pmMay 18:  (A) - Europa Conference League, kick-off 8pmMay 21:  (H) - Premier League, kick-off 1
30pmMay 28:(A) - Premier League, kick-off 4
30pmMay 13: (H) - Premier League, kick-off 3pmMay 20: (A) - Premier League, kick-off 3pmMay 25: (H) - Premier League, kick-off 8pm, live onMay 28:  (H) - Premier League, kick-off 4
30pmJune 3:  (N) - FA Cup final, kick-off 3pm
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