Chelsea were stunned 3-2 by West Ham in the London derby in the Premier League on Saturday.
Arthur Masuaku scored a stunning goal in the 87th minute to win it for the Hammers. They ended their three-game winless run in the league.
Thiago Silva put the visitors in front with a headed goal from a Mason Mount corner. Manuel Lanzini equalized from the spot following a mistake from Chelsea goalkeeper Edouard Mendy.
Mason Mount restored Chelsea's lead just before the break with a sublime goal. But another defensive lapse allowed Jarrod Bowen to restore parity for the home side.
The match was headed to a 2-2 draw but a moment of genuine quality from Masuaku. He struck an unbelievable goal with just three minutes of normal time left, sealing all three points for West Ham.
Chelsea lost for just the second time this season. It allows their rivals Manchester City and Liverpool to steal a march over them should the sides win later in the day.
Here are the player ratings for Chelsea:
Edouard Mendy - 5/10
He made an uncharacteristic mistake by giving away a needless penalty to Jarrod Bowen. However, he had no chance with West Ham's next two goals.
Andreas Christensen - 5.5/10
His positioning was questionable at various times and West Ham's second goal also flew through his legs.
Thiago Silva - 7.5/10
The Brazilian put Chelsea in front with a well-placed header that was quickly followed by a vital goal-line clearance.
Antonio Rudiger - 5.5/10
Bowen is going to haunt Rudiger in his dreams tonight as the German struggled to cope with his electric pace and movement.
Reece James - 6/10
Some usual deliveries from him in the West Ham box, although only a few were accurate.
Ruben Loftus-Cheek - 7/10
He distributed the ball well and drove forward with purpose. But he wasn't able to create many chances for Chelsea.
Jorginho - 5.5/10
The midfield maestro struggled with West Ham's press, looking nervous in possession while his passes were sloppy too. He gave a sloppy pass to put Mendy under pressure who ended up giving a penalty for West Ham's second goal.
Marcos Alonso - 6/10
He took West Ham's press head on and looked solid defensively. However, there was no attacking intent from the Spaniard.
Hakim Ziyech - 8/10
The Moroccan was unplayable in the first half with his linebreaking runs and vision. Ziyech also played a big part in Chelsea's second, brilliantly escaping his marker before laying an exquisite cross for Mount.
Mason Mount - 8.5/10
He assisted Silva for the opener from a corner and then put Chelsea ahead before half-time with a lovely goal. He looked like the only threat in the whole Chelsea side.
Kai Havertz - 6.5/10
He struggled to break West Ham's solid backline early on but grew into the match after the break. His evening came to a premature end following a nasty clash with Kurt Zouma just on the brink of half-time.
Substitutes:
Romelu Lukaku - 5/10
The Belgian's return to action was a welcome sight for the Chelsea fans but it will take him some time to return to best form.
Callum Hudson-Odoi - 5/10
He was caught in possession once and lacked real decision-making. He got into good positions but couldn't create much.
Christian Pulisic - N/A
He was barely seen after coming on.