Tottenham’s pursuit of Premier League leaders Chelsea was dealt a big blow as Manuel Lanzini’s fierce finish earned victory for London rivals West Ham.
Spurs could have narrowed the gap to a point with victory at London Stadium, but were well below par as the Hammers helped Chelsea close on the title.
Hammers keeper Adrian made first-half saves from Harry Kane and Eric Dier before Lanzini smashed in a loose ball.
Chelsea need two wins from their final four games to be crowned champions.
Tottenham must hope the Blues slip up in a favourable-looking run-in, which includes home games against three sides in the bottom seven.
Antonio Conte’s side will secure the title on Friday, 12 May if they beat both Middlesbrough and West Brom.
The Spurs players looked disconsolate as they trudged off the pitch, their heads bowed, while their West Ham counterparts – and the home fans – took great delight in harming their neighbours’ title ambitions.
“It was already going to be hard, so now it is going to be even harder,” said Dier.