Nicolas Jackson scored twice as Chelsea condemned lacklustre West Ham to a third consecutive home defeat in the Premier League.
Chelsea took a fourth-minute lead after West Ham's players switched off at a free-kick which allowed Jadon Sancho to send Jackson clear on the left.
Jackson left Edson Alvarez trailing in his wake then cut inside on to his right foot and threaded a low shot through the legs of Alphonse Areola.
The Hammers' lack of intensity was in evidence again 14 minutes later as Moises Caicedo was afforded time to slip the jet-heeled Jackson in again.
This time Jackson left behind Max Kilman and produced a deft finish with the outside of the boot, with Areola caught in no-man's land.
Chelsea effectively wrapped up the points two minutes after half-time as Jackson turned provider.
A swift counterattack culminated in the Senegal striker outfoxing the retreating West Ham defence with a clever reverse pass, and Cole Palmer fired emphatically beyond Areola.
West Ham had earlier felt aggrieved when a strong penalty appeal - checked by VAR - was turned down after Crysencio Summerville went to ground following a tussle with Wesley Fofana.
Mohammed Kudus, West Ham's most likely source of a goal, had the ball in the net before half-time but was flagged for offside while Jarrod Bowen forced Robert Sanchez to save well at his near post after the break.
Chelsea's victory puts them within two points of Premier League leaders Manchester City, while West Ham are left languishing in the bottom half, three points above the relegation zone.
BBC