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.