The Video Assistant Referee technology is being used in the Premier League for the first time this season.
After the controversial system wasn't needed for a major decision in
Liverpool's season-opening win against Norwich on Friday, it came into
play at the London Stadium.
With City already leading 2-0, Brazilian forward Jesus tapped in from Raheem Sterling's cross to seemingly make it three.
But both teams took up their positions for the kick-off, VAR
intervened to rule out the goal for a marginal offside call against
Sterling, sparking huge cheers from the West Ham fans when the decision
was announced on the scoreboard.
VAR was used in the FA Cup and League Cup last season before being
given the green light by the Premier League for the new campaign.