Man City held in blow to Premier League title bid
Pep Guardiola's side took the lead through Bernardo Silva's first-half goal, but Konstantinos Mavropanos hauled West Ham level before the interval at the London Stadium.
Just hours after Arsenal scored twice in the final minutes against Everton to seal a priceless 2-0 victory, second-placed City cracked under the pressure of trying to keep pace with the Gunners.
City have a game in hand on Arsenal but they look destined to miss out in a title race that could turn into a procession long before the finish line.