Chelsea were stunned at home by an out of form West Ham team on Saturday to miss a chance to move into second.
Frank Lampard's side, who were involved in a chaotic game in the week at Valencia, look slack and short of ideas throughout the game.
West Ham took the lead just the break when Aaron Cresswell cut inside and curled home and Chelsea had no answer.
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Had Chelsea won they could have gone into second but they stay fourth, and Jose Mourinho's Tottenham Hotspur are now just six points behind.
For West Ham this is a huge win for their manager Manuel Pellegrini and they now move up to 13th.

TALKING POINT - The win that saved Pellegrini?

West Ham came into this game on a dire run. No wins since beating Manchester United on September 22, and only two points in the league since. Throw in the League Cup humiliation by Oxford United and Pellegrini had found himself on the rocks.

West Ham United's Chilean manager Manuel Pellegrini (L) talks to West Ham United's English midfielder Mark Noble during the English Premier League football match between Chelsea and West Ham United at Stamford Bridge in London on November 30, 2019.

Image credit: Getty Images

He's by no means out of the woods, but an away win against Chelsea is a great way to buy him some time, and there was clear evidence that his players were playing for him.

MAN OF THE MATCH - David Martin (West Ham)

The 33-year-old journeyman was making his first appearance for West Ham, coming in for Roberto, who has struggled badly since joining the Hammers. Martin, the son of West Ham legend Alvin Martin, was brilliant. He made key saves throughout to keep Chelsea out, including a brilliant triple save just before half time. He put his body on the line to keep Tomori out in first half stoppage time. There were some fine defensive performances for West Ham, but Martin stood out.

West Ham United's David Martin celebrates at the end of the game during the Premier League match between Chelsea FC and West Ham United at Stamford Bridge on November 30, 2019 in London, United Kingdom

Image credit: Getty Images

PLAYER RATINGS

Chelsea: Kepa 8, James 7, Tomori 7, Zouma 7, Emerson 7, Jorginho 6, Kovacic 6, Pedro 6, Mount 7, Pulisic 8, Giroud 6. Subs: Willian 5, Kante 7, Hudson-Odoi 5.
West Ham: Martin 9, Fredericks 8, Balbuena 8, Ogbonna 8, Cresswell 8, Rice 8, Noble 8, Fornals 7, Snodgrass 7, Anderson 7, Antonio 8. Subs: Yarmolenko 5, Haller 5, Masuaku n/a

KEY MOMENTS

27' Chance West Ham! Kepa is forced into a good reaction stop from Antonio, whose bullet header from Snodgrass' cross was going in. The first save of the game, and it comes at the end you wouldn't have expected.
43' Triple Chelsea chance! Kovacic lets fly with a low drive that Martin saves but fumbles, Martin gets up and saves the rebound from Giroud and the second follow-up from Pedro. Giroud was actually offside, but Martin didn't know that - great goalkeeping!
48' GOAL! Chelsea 0-1 West Ham - Cresswell scores! Well, well, well. Fornals picks out Cresswell on the overlap, and the English left-back cuts inside Reece James and tucks it inside the bottom corner!
60' Big save by Kepa! Balbuena's thumping header from Snodrass' corner is saved well again by Kepa, who has made two or three fine reaction saves today.
67' West Ham goal ruled out! Snodgrass sends a ball to the back post with his weaker right foot and Antonio bundles it in at the far post! But VAR check it and the goal is ruled out!
89' Pulisic chance! Big opportunity for Chelsea as Kante plays in the American, but he slices his shot wide of the near post - big opening at this stage of the game.

KEY STATS

This is West Ham's first win at Chelsea since 2002.
Frank Lampard suffers back-to-back defeats for the first time as Chelsea coach.
Chelsea were looking for a fourth successive home win without conceding since January 2015.
This was Chelsea's 250th Premier League London derby. They've won 128 of them - more than any other team.
This was the first time Chelsea have drawn a blank in the Premier League at home since January 2019.
West Ham have been involved in more VAR incidents than any other Premier League team.
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