Our young Blues suffered back-to-back defeats as the Hammers overturned a two-goal deficit with second-half comeback.
Our young Blues were unable to see off the away side despite taking a two-goal lead into the half-time interval.
Donnell McNeilly put us in front and we quickly doubled the lead through a Leo Castledine penalty, but four goals which included a brace from Gideon Kadua saw West Ham keep their 100 per cent record in the Under-18 Premier League this season.
Fast start
Good build-up play from the back saw Tudor Mendel Idowu drive towards the by-line and put in a good ball which found McNeilly who controlled well and smashed into the goal to give Chelsea the first goal of the game
A good chance to double our lead came as Frankie Runham delivered into the box but Harrison McMahon’s shot went just wide.
We were on top of our opponents and Mendel-Idowu was involved again as he beat a couple of players to get into a shooting position. His eventual shot was blocked by a hand and the referee pointed to the spot.
Castledine converted from the spot as we raced into a two-goal lead.
Callum Marshall went close to halving the deficit for the away team, but his shot was saved well by Merrick.
Merrick was on hand again to make a double save from attempts by Marshall and Lewis Orford.
Patrick Kelly went close with a volley in the box that had Merrick rooted but it just went wide.
Away side comeback
Marshall made West Ham's early second-half pressure count as his smart shot after a long ball through to him found the bottom corner.
It did not take long for the away side to draw level as second-half substitute Gideon Kadua was well placed to tap the ball into the net after a drilled cross into the box.
The away team completed the turnaround when a free-kick into the box found Hammers captain Kaelan Casey who peeled off his man and headed past the goalkeeper.
West Ham scored their fourth with the last kick of the game as Kadua grabbed his second with a cool finish past Merrick.
A derby day loss for our boys as we now look ahead to our next game in the league which will be against Aston Villa away from home this weekend.
Chelsea (4-2-3-1): Max Merrick; Harrison Murray-Campbell, Travis Akomeah Frankie Runham (Tyrique George 73), Brodi Hughes (Kaiden Wilson 58); Kiano Dyer, Sam Rak-Sakyi (Michael Golding 83), Harrison McMahon; Tudor Mendel-Idowu, Donnell McNeilly (Louis Flower 73), Leo Castledine (c).
Unused sub Ted Curd.
Scorers Donnell McNeilly 5; Leo Castledine 14 (p).
Booked Donnell McNeilly 69.
Fulham (4-3-3): Finlay Herrick, Billy Bates, Oliver Scarles, Lewis Orford, Asher Falase, Kaelan Casey (c), Patrick Kelly (Gideon Kadua 58), George Earthy (Ryan Battrum 85), Divin Mubama, Callum Marshall (Daniel Rigge 69), Regan Clayton.
Unused subs Mason Terry, Favour Fawunmi.
Scorers Callum Marshall 60; Gideon Kadua 61, 90+5; Kaelan Casey 65.
Booked Regan Clayton 13; Kaelan Casey 90+4.