Match ends, West Ham United 2, Chelsea 1.
West Ham United 2-1 Chelsea
Crowd disturbances between rival fans marred the conclusion of West Ham's EFL Cup fourth-round victory over Chelsea at London Stadium.
Plastic bottles and seats were thrown towards the end of the match as hundreds of fans were involved in ugly scenes.
The flash points were a blot on what had been an entertaining night on the pitch as a much-changed Chelsea side were beaten by a cohesive and intense West Ham.
A superb Cheikhou Kouyate header before the break and an 18-yard Edimilson Fernandes strike a few minutes into the second half secured West Ham's place in the last eight and a tie against Manchester United, who beat Manchester City 1-0 in one of the evening's other matches.
Gary Cahill swept home from close range in injury time, but it was only a consolation at the end of another difficult evening off the pitch for the Hammers.
Trouble stirs once again
Security was boosted for the high-risk derby and an alcohol ban imposed as part of a "robust policing plan" aimed at minimising crowd trouble, with West Ham's new home dogged by disturbances this season.
Prior to this tie there had been nine arrests outside the stadium and 23 banning orders issued by West Ham in what has been a traumatic start to life in the former Olympic Stadium.
This match, with Chelsea allocated more than 5,000 tickets, was the biggest test yet to the police and stewards but once again trouble stirred.
An ugly atmosphere seemed to have been brewing throughout the match and as the game neared the end, riot police were deployed to maintain order as home and away fans came together in a section of the stadium concourse.
West Ham manager Slaven Bilic said he did not notice the disturbance but added that the club was "totally against it".
In a statement, West Ham said fans found to have "acted improperly" would be banned for life from attending West Ham games.
"West Ham United and London Stadium partners unreservedly condemn the behaviour of individuals involved in incidents during the fixture with Chelsea," the statement read.
Terry makes losing return
Chelsea made seven changes to the team that thrashed Manchester United 4-0 on Sunday and the most notable inclusion was that of captain John Terry, returning from injury to the centre of a three-man defence.
Terry had last played on 11 September and in his absence Gary Cahill, David Luiz and Cesar Azpilicueta have formed a backline that has registered three consecutive clean sheets in their most recent encounters.
Azpilicueta was moved to wing-back to make room for Terry and the former England international's lack of match practice played a part in the visiting defence's weakness.
Terry was beaten by Kouyate as the midfielder headed home for only his second goal of the season and the 35-year-old also played a part in the Hammers' second as Fernandes threaded his strike through his legs on the way to goal.
Chelsea boss Antonio Conte brought on his heavyweights - Diego Costa, Eden Hazard and Pedro - with the second half in its infancy but they failed to spark a comeback.
Costa, put through by the bright Willian, who was making a return following compassionate leave, was one-on-one with Darren Randolph in the closing stages of the match but chipped the ball inches wide.
Chelsea had their chances - Nathaniel Chalobah's first-half effort was tipped over the crossbar by Randolph and N'Golo Kante also went close - but West Ham were deserved winners.
West Ham 'buzzing'
West Ham manager Slaven Bilic said his team were "buzzing again" after back-to-back victories in the league following a shaky start to the season and against their London rivals they played like a team now at home in their surroundings.
Bilic's side have been holding training sessions at their new ground after taking just four points from their opening four league matches and it seems to have helped as they dominated for all but the closing stages of the match.
Off the pitch, however, this season's crowd trouble at London Stadium will be of major concern to the club.
What the managers said
West Ham boss Slaven Bilic: "It was a good game of football, it deserves to be talked about.
"I can't say we were perfect but we had a plan and the guys executed it in a great way. We were good in defending as a unit.
We were really good in keeping the ball and stretching them and playing wide. In the first half it was great and I think we deserved to be more than one up."
Chelsea boss Antonio Conte: "I must be honest, because I didn't see the situation. We were playing and I didn't see this.
"I don't like this type of situation. It's important to see always the right atmosphere.
"Above all in England, we are used to seeing the right atmosphere. This country is fantastic in this aspect. I'm sorry about this situation."
West Ham will aim to make it four successive victories as they take on Everton at Goodison Park in the league on 30 October. Chelsea boss Antonio Conte is likely to make changes for his team's league trip to Southampton, also on Sunday.
- 8KouyatéBooked at 90mins
- 2ReidBooked at 76mins
- 31FernandesSubstituted forFeghouliat 66'minutes
- 16NobleBooked at 64mins
- 30AntonioSubstituted forZazaat 82'minutes
- 10LanziniSubstituted forA Ayewat 78'minutes
- 20A Ayew
- 30David Luiz
- 34AinaSubstituted forPedroat 67'minutes
- 29ChalobahSubstituted forE Hazardat 63'minutes
- 23BatshuayiSubstituted forDiego Costaat 54'minutes
- 10E Hazard
- 19Diego Costa
- Craig Pawson
- Shots on Target
Second Half ends, West Ham United 2, Chelsea 1.
Goal! West Ham United 2, Chelsea 1. Gary Cahill (Chelsea) right footed shot from very close range to the bottom right corner. Assisted by César Azpilicueta following a set piece situation.
Cheikhou Kouyaté (West Ham United) is shown the yellow card for a bad foul.
Foul by Cheikhou Kouyaté (West Ham United).
David Luiz (Chelsea) wins a free kick in the defensive half.
Corner, West Ham United. Conceded by Asmir Begovic.
Attempt saved. Dimitri Payet (West Ham United) right footed shot from the centre of the box is saved in the bottom right corner.
André Ayew (West Ham United) wins a free kick on the right wing.
Foul by Gary Cahill (Chelsea).
Foul by Angelo Ogbonna (West Ham United).
Diego Costa (Chelsea) wins a free kick in the attacking half.
Mark Noble (West Ham United) wins a free kick on the right wing.
Foul by Willian (Chelsea).
Attempt missed. Diego Costa (Chelsea) left footed shot from the right side of the box is close, but misses to the right.
Attempt missed. André Ayew (West Ham United) header from very close range is close, but misses to the right.
Substitution, West Ham United. Simone Zaza replaces Michail Antonio.
Attempt missed. Eden Hazard (Chelsea) right footed shot from the right side of the box is close, but misses to the right.
Corner, Chelsea. Conceded by Pedro Obiang.
Corner, Chelsea. Conceded by Winston Reid.
Attempt blocked. Diego Costa (Chelsea) left footed shot from outside the box is blocked.
Substitution, West Ham United. André Ayew replaces Manuel Lanzini.
Foul by Mark Noble (West Ham United).
N'Golo Kanté (Chelsea) wins a free kick in the attacking half.
Attempt blocked. David Luiz (Chelsea) right footed shot from outside the box is blocked.
Winston Reid (West Ham United) is shown the yellow card for a bad foul.
Foul by Winston Reid (West Ham United).
Diego Costa (Chelsea) wins a free kick in the defensive half.
Attempt missed. Willian (Chelsea) left footed shot from the right side of the box misses to the left.
Sofiane Feghouli (West Ham United) wins a free kick in the defensive half.
Foul by Oscar (Chelsea).
Mark Noble (West Ham United) wins a free kick in the attacking half.
Foul by Diego Costa (Chelsea).
Attempt missed. Oscar (Chelsea) right footed shot from the centre of the box is close, but misses to the left.
Corner, Chelsea. Conceded by Cheikhou Kouyaté.
Corner, West Ham United. Conceded by David Luiz.
Substitution, Chelsea. Pedro replaces Ola Aina.
Substitution, West Ham United. Sofiane Feghouli replaces Edimilson Fernandes.
Mark Noble (West Ham United) is shown the yellow card for a bad foul.
Foul by Mark Noble (West Ham United).