The Hammers went ahead through Angelo Ogbonna in the 38th minute, but fell apart within the space of nine minutes 15 minutes into the second-half.
Arsenal scored thrice through Gabriel Martinelli (60th minute), Nicolas Pepe (66th minute) and Pierre-Emerick Aubameyang (69th) to land a blow on West Ham, and former Gunners star Ian Wright believes they threw their lead away.
The Arsenal legend reacted to the result thus on Twitter:
Yes and he very clearly got a response from the group at HT 👏🏾 West Ham threw that away though!!!
— Ian Wright (@IanWright0) December 9, 2019
West Ham were solid at the back in the first-half, with Arsenal failing to register one shot on target and only getting into their box for the first time after 30 minutes.
The hosts were still impressive up until the 60th minute – when everything fell apart – and they couldn’t come back from it.
The Hammers have taken just four points from their past nine league games and have conceded thrice in three successive home games, suffering three straight league defeats at home for the first time since 2015.
Last night’s result means they remain just one point and two spots above the relegation zone, and Saturday’s six-pointer against Southampton could have a huge say on Pellegrini’s future.