Arsenal came from behind to end their nine-match winless streak as Freddie Ljungberg enjoyed his first victory as interim manager at the expense of West Ham.
Gabriel Martinelli marked his full Premier League debut by side-footing an equaliser which cancelled out Angelo Ogbonna’s deflected first-half opener.
Within nine minutes, Nicolas Pepe had curled a magnificent second into the top corner and Pierre-Emerick Aubameyang fired in a third.
The Hammers remain a point above the relegation zone in 16th and face a trip to third-bottom Southampton on Saturday. Arsenal move up two places to ninth.
Meanwhile West Ham manager Manuel Pellegrini is “not worried about relegation” from the Premier League even though his side are above the bottom three by only a point.
Last night 3-1 defeat was a seventh loss in nine games.
“In our last five games at home we got one draw and conceded three goals in our last three. I am more worried about that,” said the Chilean.
Some people within the club believe Pellegrini, 66, could lose his job if the Hammers are beaten at St Mary’s.