West Ham earned their first three points at home in the Premier League this season after defeating Manchester United 3-1 at the London Stadium to condemn José Mourinho's men to a fourth defeat of the season and a second in as many games.
Felipe Anderson scored his first league goal in claret and blue since joining for a club-record fee of £36m in the summer, to put the hosts in front before Andriy Yarmolenko's strike took a wicked deflection off Victor Lindelöf to double the lead before half-time.
Substitute Marcus Rashford then flicked home following a corner to reduce the deficit for the visitors, but Marko Arnautović slotted in to restore the east London side's two-goal lead and seal the victory, piling the misery on the Old Trafford club, who were beaten by Championship side Derby County in the Carabao Cup in midweek.
Check out our breakdown of the game below.
WEST HAM UNITED
Key Talking Point
After starting the season so poorly, West Ham have roared back in recent weeks, with the draw against Chelsea and win at Everton proving they are now a back in form.
They took advantage of a poor United side on Saturday, looking fiercer and more determined to emerge with three points.
Their forward trip of Arnautovic, Yarmolenko and Anderson ran United's defence ragged all afternoon long, and judging on this evidence, the Hammers should be looking to climb the table in the coming months after a shoddy start.
Starting XI: Fabianski (7); Zabaleta (8), Balbuena (7), Diop (7), Masuaku (7); Rice (7), Noble (7), Obiang (7); Anderson (9*), Arnautovic (7), Yarmolenko (6).
Substitutes: Snodgrass (6), Antonio (6), Diangana (N/A)
STAR MAN - It was Felipe Anderson who got the ball rolling in the fifth minute, tucking home from close range after excellent work from Pablo Zabaleta, and he made good of his excellent start with a great display over the 90 minutes.
The Brazilian was always available and gave Ashley Young plenty of problems on United's left hand side of defence.
WORST PLAYER - Pedro Obiang was pretty anonymous throughout his showing, so the central midfielder earns this accolade.
Key Talking Point
Where do you even start?
Paul Pogba, again, looked out of sorts, and was hooked shortly before Marcus Rashford pulled one back for the visitors.
The speculation surrounding the Frenchman and United manager Jose Mourinho will continue, but Saturday was the perfect time for Pogba to stand up and deliver a great performance.
Sadly for United fans, he couldn't, as West Ham's midfield took the initiative and kept the former Juventus star on the periphery of the game.
Starting XI: De Gea (5); Young (5), McTominay (6), Smalling (7), Linedelof (4), Shaw (6); Fellaini (6), Matic (6), Pogba (6); Lukaku (6), Martial (6).
Substitutes: Rashford (7*), Mata (6), Fred (6)
STAR MAN - There weren't exactly many candidates for this award on United's side, but Marcus Rashford was lively as a substitute and helped claw the Red Devils back into the game with an instinctive finish from a corner.
Sure, Arnautovic scored three minutes later to secure the win for the Irons, but still, Rashford helped.
WORST PLAYER - Victor Lindelof had something of a stinker, netting an own goal after he turned Yarmolenko's shot past David de Gea to give the hosts a two-goal lead.
McTominay unsurprisingly didn't impress as a centre back, while the away side couldn't make use of Fellaini's noted aerial gifts.
Now unbeaten in their last four games, West Ham face a trip to Brighton next week as they look to continue their impressive form.
As for United, they'll need to dust themselves down and get ready for Champions League action, with Jose Mourinho's side entertaining La Liga outfit Valencia before another Old Trafford clash against Newcastle.