The Hammers - who sit 17th in the table - took the lead in a crucial London derby, with David Moyes' side fighting for their lives to avoid the drop.
A West Ham corner resulted in a scramble in the Chelsea penalty area, with Thomas Soucez capitalising to prod home past a helpless Kepa Arrizabalaga.
The defender was engaged in a battle for the ball with Chelsea defender Cesar Azpilicueta, while team-mate Michel Anontio was stranded on the floor, in between the ball and the keeper.
VAR subsequently reviewed the goal for around three minutes, eventually ruling that Anontio's head was offside, with the rules stating a goal must be ruled out if a player is "clearly obstructing a goalkeeper's line of vision".
Absolute *SCENES* at the London Stadium! 🤯
West Ham think they've taken the lead against Chelsea but VAR disallows it for offside! 😳
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The Hammers were then dealt a further blow, with Willian giving the visitors the lead after the in-form Christian Pulisic was brought down in the area.
West Ham did hit back before half-time, however, Soucek again scoring from a corner - this time the goal standing, the score 1-1 at half-time.
However, it is the VAR controversy that remains the major talking point. And for Lineker, it's clear to see what he thought of the decision.
"Even before the decision I’ve started to really loathe VAR. what are they doing?" he asked on Twitter.
Even before the decision I’ve started to really loathe VAR. what are they doing?a a a a — Gary Lineker (@GaryLineker)July 1, 2020
Total disgrace VAR West Ham cheated out of a goal. Took them 5 mins to study.— Lord Sugar (@Lord_Sugar)July 1, 2020
Wait until the start of the second half... #VAR might stop the game and rule out Soucek’s header as his left foot was at a 34* angle and in the Mayan calendar 34 means Red and West Ham’s claret isn’t technically defined as Red.
They’re just checking the definition of Red now.— Jaack (@Jaack)July 1, 2020
— Brandon Merriam (@nytrydr1818)July 1, 2020