Nuno Espirito Santo's resurgent Hammers were on course for a third straight Premier League win at the interval, having ruthlessly punished a lacklustre Chelsea display.

Having made six changes to the team that beat Crystal Palace last week, Liam Rosenior saw his team fall behind when Jarrod Bowen's seventh-minute cross curled all the way in. 

Crysencio Summerville's fizzing finish doubled West Ham's tally in the 36th minute, leading to Rosenior making three changes at half-time, introducing Joao Pedro, Wesley Fofana and Marc Cucurella, and all three had key roles to play in Chelsea's fightback.

Fofana stepped out of the backline to supply a wonderful cross as Joao Pedro made it 2-1 in the 57th minute, then Cucurella pounced with a diving header to make it 2-2, after Liam Delap nodded against the crossbar under pressure from Maximilian Kilman.

Jean-Clair Todibo somehow prodded against the post with the goal gaping, and Chelsea made that reprieve count as Joao Pedro cut the ball back for Fernandez to sweep home, on the eve of the three-year anniversary of his arrival at Stamford Bridge.

Tempers then boiled over in the closing stages, and Todibo was sent off for grabbing Joao Pedro around the throat, compounding West Ham's woes.

They remain 18th, five points adrift of Nottingham Forest, while Chelsea climb into the top four ahead of Manchester United's meeting with Fulham on Sunday.