Myers’s Blues were the more dominant side though and Fiabema thought he had restored parity after 15 minutes, but his goal was ruled out for offside after being set up well by Ben Elliott in the build-up.
Fiabema did get on the scoresheet soon after though, firing home 10 minutes before the break with a smart finish after capitalising on some slack West Ham defending.
A lengthy stoppage following a clash of heads between Thierno Ballo and Aji Alese meant there would be a lot of additional time added on, with that proving decisive as the hosts grabbed a winner through Ashby despite Chelsea previously looking the more likely to score.
The Hammers saw out the final few minutes to secure all three points, with Chelsea’s next PL2 game seeing us travel north to take on Manchester City on September 11.
Chelsea: Bergstrom, Rankine, Mbuyamba (c), McClelland, Humphreys, Elliott, Soonsup-Bell, Ballo, Fiabema, Vale, Frith.
Subs: Sharman-Lowe, Ryan, Simons, Haigh, Nunn.