Substitute Kai Havertz scored a late winner as Chelsea came from behind to record a dramatic victory over West Ham, who had a 90th-minute Maxwel Cornet equaliser ruled out.
The Hammers frustrated Chelsea in a first half that saw plenty of home possession but no shots on target for either side, and looked to have executed their gameplan to perfection when Michail Antonio scored from a rare attack after 62 minutes.
The forward bundled in from close range after Blues goalkeeper Edouard Mendy failed to deal with a corner, but the visitors' lead was wiped out 14 minutes later.
Chelsea, on the back of a record summer of spending and with £70m arrival Wesley Fofana making his debut, had struggled to break down David Moyes' side before Ben Chilwell snuck in to level from a tight angle shortly after coming off the bench.
It sparked a frantic finish, with Cornet almost winning it late on for the visitors, only to see his header come back off the post and the Blues immediately score themselves through a clinical Havertz header from Chilwell's cross.
There was still time for more drama as Cornet pounced, but only after a foul on Mendy that was awarded once referee Andrew Madley consulted the pitchside monitor.
Afterwards, Blues manager Thomas Tuchel said: "We were lucky today to get the VAR decision in our favour, which was for me the correct decision. We want to turn the game around and keep the three points.
"They do this to every team, it is so hard to create spaces, to create chances. They defend deep and with bodies and physicality. It is hard to find a consistent rhythm, then you go 1-0 down it is almost impossible - to keep believing was very important.
"To get the opener from the bench from Chilly and then from Kai was important because we want spirit. If we have a strong bench we have a higher chance to win.
"You need be tough, I know they can do it. It is also down to the situation, the transfer window is closed, everyone knows he is in the group. We need to improve consistency and this is not over."
