Crystal Palace dealt a heavy blow to West Ham’s ambitions of playing European football next season with a 5-2 victory at Selhurst Park.
Palace, who had not previously scored more than three goals in a league contest this season, led by four inside 31 minutes, opening the scoring with a Michael Olise header before Eberechi Eze made it two with a superb bicycle kick.
Emerson intensified the Irons’ woes when he turned the ball into his own net before Jean-Philippe Mateta got on the scoresheet just after the half hour mark.
Antonio clawed one back for the visitors before the break but Mateta bagged his second in the 64th minute to re-establish the four-goal buffer.
Just as it looked to be the exclamation mark on a thumping victory, Palace keeper Dean Henderson was caught out and allowed Tyrick Mitchell’s backpass to skip past his foot and into the hosts’ net.
Defeat leaves West Ham eighth, two points adrift of Newcastle and Manchester United above them who both have two games in hand.
Joachim Andersen’s lovely clipped cross set up Olise to nod past Lukasz Fabianski for the seventh-minute opener as Palace began in fine fashion.
Mitchell nearly made it two, blazing over after he was released by Eze, who soon double Palace’s lead.
Fabianski got just enough of his boot on Mateta’s low effort but the ball rebounded in the path of Eze, who obliged in acrobatic style with a magnificent bicycle kick.
Palace were three goals to the good when Will Hughes clipped the ball towards an onrushing Daniel Munoz at the back post, where the unfortunate Emerson instead deflected it past his own keeper.
The chances kept coming, all for Palace, who stole the ball away from the Hammers in midfield, eventually allowing Olise to send a delivery across the face of goal for Mateta to tap home.
The Hammers finally enjoyed a spell inside the hosts’ final third shortly after the half hour mark, when Angelo Ogbonna nodded one of the visitors’ lone chances over the bar.
It was the beginning of a slightly more settled period for David Moyes’ men, who clawed one back in the 40th minute when Antonio poked Tomas Soucek’s header past Henderson, the goal standing after a VAR check.
The Palace keeper was called into action to deny Mohammed Kudus’ low effort, clinging to the ball in his lap as opportunistic white shirts buzzed around him at the goal-line to pounce on a spill that never came, and it was the Eagles who came closest before the break when Andersen nodded over.
Henderson claimed Emerson’s cross to kick-start the second half when Moyes made a pair of substitutions, replacing Ogbonna with Aaron Cresswell and Soucek – who had been booked late in the first period – with Ben Johnson.
Fabianski made a big diving save to deny Eze and Palace were dealt a blow when Adam Wharton, who has shone since his January signing, was forced off after colliding with Emerson and replaced by Naouirou Ahamada just past the hour mark.
Mateta restored the hosts’ four-goal advantage less than three minutes later, latching on to a pass from Eze through the legs of Kurt Zouma and into the bottom corner.
Just as the Frenchman’s second strike looked to settle the scoreline, Palace’s season-long habit of conceding late goals came back to haunt them, only this time it was one entirely of their own doing – Henderson’s gaffe putting a late downer on his side’s emphatic triumph.