David Moyes says he has "lost faith in VAR" after Maxwel Cornet's late equaliser was contentiously chalked off to ensure Chelsea won 2-1 after a frantic finale at Stamford Bridge on Saturday.
Substitute Cornet, who struck the post with a free header before Kai Havertz's late winner (88), thought he had redeemed himself until VAR Jarred Gillett advised referee Andy Madley to go to his monitor to check Jarrod Bowen's slight touch on Chelsea goalkeeper Edouard Mendy.
West Ham manager David Moyes described the decision as "rotten" and "ridiculous" and accused Mendy of feigning injury, while Chelsea boss Thomas Tuchel said "there is a reason it went in our favour".
Chelsea roared into life after Michail Antonio poked West Ham in front from close range (62), with Ben Chilwell equalising (76) before setting up his fellow substitute Havertz for the winner.
Tuchel's side getting back to winning ways moves them momentarily up to fifth, while West Ham languish in 17th just above the relegation zone after claiming only one win from their opening six games.
How Chelsea snatched a late win with the help of VAR
Chelsea were looking to put a frustrating August behind them against West Ham, but it was more of the same for most of the first half as they struggled to trouble the visitors, with ex-Blues defender Kurt Zouma putting in a solid display.
The best chance of the half fell to Christian Pulisic, but his tame effort was blocked by West Ham's record-signing Lucas Paqueta on his full league debut. Chelsea midfielder Mateo Kovacic also tested the West Ham goal from the edge of the area, but fired narrowly wide.
Neither team was able to register a shot on target in what was a forgettable first half, with Pablo Fornals hitting West Ham's only shot of the half over the bar as Chelsea's expensive new back line - which included £75m debutant Wesley Fofana - had a largely quiet opening 45 minutes.
It was a fast start to the second half for both teams, but West Ham made the breakthrough as Declan Rice capitalised on some weak goalkeeping by Mendy from a corner to set up Antonio, who tapped in with the ball basically on the line.
The arrival of Havertz and Chilwell off the bench made all the difference for Chelsea as the left-back produced a smart front-post finish to level the game after taking down Thiago Silva's flighted delivery before turning provider for the Germany forward as he claimed his first goal of the season with an exquisite first-time finish.
Cornet thought he had won the game for West Ham prior to Havertz's goal when Said Benrahma's cross found him free at the back post only to watch his header strike the post. The West Ham forward, though, can feel aggrieved after VAR harshly ruled out what would have been an 89th-minute equaliser for a soft challenge on Mendy by Bowen.
Tuchel subs make the difference
Thomas Tuchel made five changes from the Chelsea team that lost 2-1 to Southampton, sending a message to some of his more regular starters after an underwhelming start to the season.
Mason Mount, Havertz, Chilwell and Jorginho watched on from the bench as Chelsea struggled to create any clear-cut chances for the first hour or so.
But their arrival - along with the impact of youngster Armando Broja, who produced another impressive cameo - injected some much-needed energy into the contest and turned the tide for Chelsea, as they responded impressively to going a goal down.
It was Chilwell who stole the show, though, providing a goal and an assist from the left wing-back position. Tuchel said after the game he looks like he is "lacking rhythm" in training, but the England international was supremely sharp when he came on and was decisive off the bench. A timely reminder of his quality ahead of the World Cup.
Pierre-Emerick Aubameyang's presence in the stands appeared to jolt Havertz into life. Questions were being asked of the Germany international before this game after he failed to score or assist in the opening five matches. But he is off the mark now and is sure to be buoyed by his performance off the bench and an exquisite first-time finish.
Moyes: I've lost faith in VAR
West Ham manager David Moyes was scathing in his assessment of VAR Gillett for his decision to advise referee Madley to go to the screen to take another look at Maxwel Cornet's late equaliser.
"The goalkeeper comes to take it and fumbles it out of his hands," said Moyes. "Then he acted as if it was a shoulder injury. I'm amazed that VAR sent the referee to the screen.
"I thought when I saw it, 'Even if he goes to the TV, there's no way he's overturning this'. It was a ridiculously bad decision.
"I think I question VAR today as much as the referee. The referee should have stuck to his own guns and been big enough to do what he said.
"I've had a chance to look at three or four angles, which they have, so there is no excuse for VAR. Today there is no excuse for that not to be a goal, none whatsoever.
"The sad thing is that this is the level of our elite refereeing at the moment. The goalkeeper tried to do the same thing with the first goal as well, he tried to fake an injury for the first goal as well.
"They've got new people in charge. I've lost faith in them today."
Tuchel: It was a foul on Mendy
Chelsea boss Tuchel took an opposing view and felt it was a foul on his goalkeeper, arguing there was an offside infringement for West Ham's opener as well.
"There's a reason it went in our favour," said the German. "I don't know if everyone shares the opinion - it's a foul. The goal that we conceded in very similar in the build up to the situation at Tottenham.
"The second corner should never have been a corner. When the shot came from Bowen and we had the shot from Edu, it was a clear offside position from Antonio.
"I don't know how [it can be] you can foul when you're in an offside position against a goalkeeper and get a corner. That was the build up to the first corner, it was similar to Tottenham but I stop talking."
Opta stats: Rare Chelsea second-half comeback
- Ben Chilwell has been directly involved in four Premier League goals against West Ham (one goal, three assists), only against Southampton has he been involved in more in the competition (5).
- Chelsea came from behind to win a Premier League home game after they'd conceded the first goal in the second half for the first time since January 2009, against Stoke City (also 2-1).
- West Ham are winless in their last six Premier League London derbies (D1 L5), since a 3-2 victory against Crystal Palace in January.
- Chelsea have won four of their last five Premier League games against West Ham (L1), while they've won three in a row at home against the Hammers for the first time since March 2013.
- Michail Antonio has scored 13 Premier League goals in London derbies for West Ham, only Carlton Cole (14) has netted more in such games for the Hammers in the competition.
What's next?
Chelsea's next fixture is in Croatia on Tuesday September 6, when they begin their Champions League campaign away to Dinamo Zagreb, kick-off at 5.45pm.
The Blues are then back in Premier League action on Saturday September 10, when they will make the short journey across west London to Fulham, kick-off at 12.30pm.
West Ham also begin their European journey in midweek, when they host Steaua Bucharest on Thursday September 8, kick-off at 8pm.
The Hammers will then host Newcastle in the Premier League on Sunday September 11, kick-off at 2pm, live on Sky Sports.