Chelsea subs: Kepa, Lukaku, Pulisic, Werner, Saul, Barkley, Hudson-Odoi, Azpilicueta, Sarr.
Chelsea starting XI: Mendy, Silva, Rudiger, Christensen, James, Jorginho, Loftus-Cheek, Alonso, Mount, Ziyech, Havertz.
West Ham subs: Areola, Yarmolenko, Fornals, Vlasic, Noble, Benrahma, Masuaku, Kral, Ashby.
West Ham starting XI: Fabianski, Zouma, Dawson, Diop, Johnson, Rice, Soucek, Coufal, Bowen, Lanzini, Antonio.
Chelsea did the league double over West Ham last season. They last won three in a row against them in the top flight between March 2010 and April 2011.
West Ham have lost two of their last four Premier League London derbies (W1 D1), as many as they had in their previous 10 such contests (W4 D4). However, they won their last derby match in the competition against Tottenham Hotspur, last winning consecutive meetings with London clubs in January 2019 during a run of three.
West Ham United have won three of their last six home Premier League matches against Chelsea (D1 L2), as many as they had in their previous 14 such encounters against them in the competition (D3 L8).
Chelsea have won their last seven away London derbies in the Premier League, an all-time record in the top four tiers of English football. The Blues have kept six clean sheets in this run, with their only goal conceded to Christian Benteke in April.
Hello and welcome to live coverage of West Ham vs Chelsea in the Premier League, kickoff 12.30pm UK time. The match takes place at the London Stadium.
Kickoff - we are underway in London.
Chelsea with plenty of possession so far. They have the first freekick to deliver into the box.
James delivers from an inside right position for Chelsea but West Ham clear well.
Rudiger plays a long pass over the top for Chelsea but it's totally overhit and runs through to Fabianski.
A half chance for Ziyech now as a James low cross reaches him but the Moroccan's shot is charged down.
Just wide! Thiago Silva gives the ball away, Bowen drives at the Chelsea defence and sends his shot just wide.
James shoots from 25 yards for Chelsea but it doesn't really trouble Fabianski.
Close! Soucek reaches Antonio's cross and nods it just wide of Mendy's goal. The goalkeeper was rooted to the spot and that was nearly 1-0.
Havertz pokes a shot wide for Chelsea at the near post but the offside flag had been raised anyway.
Chelsea with 77% possession so far in this match.
Rice delivers a freekick for West Ham after a foul on Lanzini. Zouma attacks it but Loftus-Cheek heads away for a corner.
CHANCE! West Ham's corner from Lanzini causes chaos. Dawson flicks on, it hits Soucek and falls back down for Dawson to shoot but it's straight at Mendy.
Yellow: Jorginho is carded as he falls over and handballs on purporse. His reaction also contributed to it as he wanted a freekick.
CHANCE! Chelsea have a long period of possession. The ball reaches James to cross from the right half space and Havertz heads towards goal but doesn't generate the power to beat Fabianski.
GOAL, CHELSEA! THIAGO SILVA! Mount's corner from the right is headed home unchallenged as West Ham's zonal marking is exposed. West Ham 0-1 Chelsea.
Off the line! West Ham nearly level right away as Coufal strikes a shot which beats Mendy and is cleared by Thiago Silva behind him.
Loftus-Cheek strikes a shot from range but it's half blocked and loops up into the goalkeeper's grateful arms.
Alonso delivers low from the left for Chelsea towards Havertz but Diop and Zouma both slides in to clear from the German.
Penalty to West Ham! Jorginho plays a back pass, Mendy tries to shield from Bowen and ends up clattering him from behind. Clear penalty.
GOAL, WEST HAM! LANZINI! He strides forward and sends Mendy the wrong way from the penalty. West Ham 1-1 Chelsea.
Chelsea threaten again now and Ziyech gets the ball in the box but goes alone instead of passing to Havertz and his effort is blocked.
GOAL, CHELSEA! MOUNT! Rice gives it away, Ziyech receives on the left and hits a big diagonal which Mount volleys past Fabianski at the near post. A lovely strike. West Ham 1-2 Chelsea.
Half time. Goals from Thiago Silva and Mount for Chelsea with a Lanzini penalty in-between to level. Join us in 15 minutes for the second half. West Ham 1-2 Chelsea.
+3' Zouma covers over to challenge Havertz. It looks a decent penalty shout but VAR says no penalty. Both players are down getting treatment and look in pain.
+2' SUB for West Ham: Masuaku on for Johnson at left wingback due to injury.
Added time: 2 minutes
Wide! Antonio shoots straight from kickoff but sends it wide of Mendy's goal.
Kickoff! The second half gets started. One change: Lukaku replaces the injured Havertz.
Chelsea have a couple of corners. The one bounces off Diop and bounces just wide of his own goal.
Antonio muscles Christensen off the ball for West Ham and tries to slide Bowen through on goal. But Loftus-Cheek showed great pace to clear anyway. The flag had gone off.
Rudiger leads a counter with a brilliant run but his pass is ahead of Ziyech who skews the ball well wide.
GOAL, WEST HAM! BOWEN! West Ham attack down the right and Bowen cuts inside and fires a shot through Christensen's legs and past the dive of Mendy. West Ham 2-2 Chelsea
West Ham launch a high ball into the area and Mendy has to parry against Zouma and then dive on the loose ball.
SUB: Hudson-Odoi replaces Ziyech.
Chelsea play some good stuff down the right with Mount but his cross is too heavy and Rice heads it clear.
Hudson-Odoi tees up Mount to shoot but he fires his effort straight at Fabiankski. He should have done better.
Rudiger slides a pass for Lukaku but his touch is poor. Zouma is hobbling, it looks like he has injured his calf.
Zouma can't continue it seems, Fornals is warming up for West Ham.
James' cross is cleared away for a corner. He takes it himself but it comes to nothing.
SUB for West Ham: Fornals on for Zouma. A switch to a back four.
SUB for Chelsea: Pulisic on for Alonso. Hudson-Odoi to left wingback.
CHANCE! West Ham should take the lead. Antonio muscles Hudson-Odoi off the ball and fires a cross into the area for Bowen, who slides in and sends a huge opportunity just wide of the target.
Just wide! Hudson-Odoi tees up Jorginho to shoot from the edge of the area and it deflects just wide. The corner comes in and Loftus-Cheek knocks it down but Dawson gets it clear.
A spell of Chelsea pressure comes to an end as Lukaku heads wide under intense pressure from the West Ham centre backs.
Bowen bursts down the left and takes on James and Christensen for West Ham but the ball bounces back off the winger and out for a goalkick.
SUB for West Ham: Benrahma comes on for Lanzini.
GOAL, WEST HAM! MASUAKU! West Ham have made it 3-2. The ball reaches Masuaku down the left and his cross swerves at the near post and beats Mendy. Maybe the goalie could have saved that. West Ham 3-2 Chelsea.
Fornals plays an excellent pass around the corner for Antonio to chase for West Ham but Christensen defends excellently.
CHANCE! Antonio slides a pass down the side for Bowen who looks border-line offside and the winger sidefoots well wide.
FULL TIME. West Ham come from 2-1 down to score in the 56th and 87th minutes to win the match. Moyes is delighted. West Ham 3-2 Chelsea. Thanks for joining us.
+4' Yellow card: Christensen trips Antonio and is booked.
+2' Yellow! James is carded for Chelsea.
Added time: 4 minutes.