Thanks for tuning in this afternoon. Stay with Sky Sports for the full report and all the reaction.
That's it! The full-time whistle seals a 2-0 Chelsea win.
Lampard is looking for the big finish but his attempted cross is seen off by the head of Demel.
Oscar's flick doesn't quite come off and it rolls back to Jaaskelainen as the clock ticks down.
West Ham try to get forwards in these dying minutes but Mikel gets the ball away from Cole.
There's a late Hammers corner which Jarvis takes. Carroll rises to win it with a header but he can't keep it down - the story of his game today.
Another superb save from Jaaskelainen as Hazard comes close again with a deflected shot fizzing up off the surface. Three minutes of stoppage time will be added.
Another late chance for Chelsea as Azpilicueta squares a cross to Lampard but the Hammers defence hold firm to deny him.
Carroll brings down the ball and manages to slip it on to Collison on the edge of the box but his attempted shot is blocked by Terry.
A lovely turn from Oscar sees him set up Lampard perfectly in the box but his lash at the ball sends it high over the bar in an uncharacteristic gaffe.
Mata makes way for John Obi Mikel after a superb performance for the Blues.
Ba tries a backheel in the box, looking for the advancing Mata, but he's not behind him to meet it as the Hammers recover.
Cole prompts a quick-thinking save from Cech as he pokes Jarvis' cross towards goal and it's a nervy moment for the hosts.
Chelsea are calling for a penalty again after Reid appears to haul down Ba but the ref again isn't interested.
Jarvis gives the ball away and Mata takes advantage, pairing up with Oscar on a break. The latter sets up the Spaniard in the box but his right-footed shot is dragged wide.
Mata's delivery is met by Cahill but his free header can't find its target.
Cole attacks down the left for Chelsea and tries to find Oscar in the box but it's cut out by Demel for a Blues corner.
Cole comes on for West Ham as Vaz Te makes way.
Vaz Te looks to make tracks into the box but Cahill ensures his run is stopped short.
Hazard finds Ba on the charge but he hesitates and can't get a shot away as Reid hunts him down and gets a challenge in.
Terry makes his entrance to a huge cheer from the Chelsea fans as Luiz hobbles off.
Luiz is calling to come off, looking in pain, and it looks like Terry will be making an appearance after all.
Jarvis is caught as he tries to clear the ball and it goes back to Jaaskelainen. The long ball is nodded on by Carroll but Ramires intervenes.
Oscar makes his first contribution with some lovely play down the left with Mata to tee up Hazard but his shot is blocked by O'Brien.
Demel barges Luiz as he battles the Brazilian on the right of the Blues' half to hand Chelsea the free-kick.
It's Luiz who takes this one from far out on the left but his attempt goes horribly wrong and is nowhere near troubling the keeper.
There's another booking as Demel sees yellow for a clip on Hazard, on another charge. Another free-kick for Chelsea.
The free-kick from a long way out is taken by Lampard. It takes a deflection off the wall to take the pace out of it and allows Jaaskelainen to make a relatively comfortable save.
The first caution of the game goes to Hammers captain Reid after he drags back Mata, who's on a surging run towards the box.
Chelsea make their first change as Moses makes way for Oscar.
There's a call for handball for the Chelsea fans after the ball appears to fly up and strike Reid on the arm but the ref isn't interested.
O'Neill tries to catch Cech unawares in the box but his hasty flick of a shot doesn't trouble the goalkeeper.
Tomkins puts in a cross from the right after some build-up play with Demel but it's a poor effort and it goes straight into Cech's waiting gloves.
O'Neill nutmegs Cole to find Vaz Te but Luiz intercepts his ball. Chelsea then go on the break but Hazard can't pick out a final pass.
Azipilicueta launches a throw-in for Chelsea on the right and it finds Hazard in a dangerous area but O'Brien subdues the threat.
Taylor comes again with his second corner but hits the first man again as Lampard sweeps it away to safety.
Hazard nods the ball behind to hand the Hammers a corner - their second of the game. Cole is there to head the delivery away but it comes straight back in and Ramires puts it behind.
Chelsea are in control as they swap passes in midfield but Tomkins makes an effective first contribution as he slides in to rob Luiz of the ball.
There's another change for West Ham as Collins makes way for James Tomkins.
Luiz and Carroll battle again to meet another Jarvis cross and once again it goes Chelsea's way. The Hammers striker is looking a threat though.
The dangerous duo Mata and Hazard pair up again inside the Hammers' box until the former gets a shot away but O'Brien is there to block it.
Jarvis makes a good run down the left and plants a cross in at the far post. Carroll and Luiz both rise to meet it and it goes behind, with the ref ruling it's a goal-kick.
O'Brien is hustled out of possession by Ramires as Chelsea get the ball away but West Ham are straight back on it as Carroll finds Jarvis with a lovely touch in midfield.
On the break, Carroll does well to shrug off Cahill in midfield and surge off on a run but scuffs his eventual shot so that Cech has it easily covered.
Chelsea aren't in any hurry now but are still trying to build another attack, as Mata and Lampard pair up on the edge of the area.
Another big chance for Chelsea as Jaaskelainen again saves with his feet against Mata before getting a crucial touch to keep it away from Lampard, loitering in front of goal.
There's a chance for the Hammers as Collison gets a shot away from just inside the box to prompt a stretching save from Cech.
Another chance for Chelsea Lampard comes close but can't apply the all important finish. West Ham have a job on their hands now.
It's a lovely one-two between Hazard and Mata as the Belgian breaks into the box and defies two defenders before slicing his shot home into the bottom left-hand corner.
GOAL! HAZARD FOR CHELSEA! 2-0!
Hazard shows some lovely skill in midfield to slip the ball through the legs of O'Brien and he flicks the ball onto Mata.
A poor Carroll throw allows Mata to snatch the ball away and through to Moses but he is held up down the left.
Azpilicueta appears to have been winded after a tussle with Vaz Te following his charge down the right but seems ok.
It's West Ham that get things started this half and they win an early throw on the right of the Blues' end. Taylor tries for an instant impact with his attempted cross in from the right but it goes straight to Cech.
Matthew Taylor replaces Diame at the break for West Ham in the first and only change.
Thanks for all your feedback. It's almost time to get back underway - enjoy the second half!
@connor_grace_91 tweeted - "frank lampards gets his 200th goal for chelsea wat a legend best chelsea player ever in my eyes no doubt!"
@CFCInformative tweeted - "Demba Ba... Only ''1'' goal in lat 9 games!!! Hope we haven't got another torres on our hands!!! We should be 4 goals up."
Jermaine Aryeetey says - "Great game ! The blues have had a lot of chances and jaaskalainen has been outstanding. I hope we go out early in the second half, get the second and kill the game off. We have to capitalise as spurs have lose... COYB."
Toby Day wrote in - "Hi, a good first half with CHELSEA in front. Good play by Lampard! My prediction is a 2-0 or 3-0 win! I reckon Ba will score the way he's been playing so far. Lets see how it goes!"
@MattCrowe96 has tweeted - "West Ham Need to step up their game if we are going to get a result."
Get in touch with your thoughts on the opening half by emailing email@example.com or tweeting @SkySportsRachG.
That's it for this half as the whistle blows for half-time and it's Chelsea 1 West Ham 0 after an entertaining start to this derby clash.
Good strong defending from Collins denies Ba as he creeps forward again for Chelsea and it's a Jaaskelainen goal-kick.
It's Collison's that climbs to get Hazard's corner away. At the other end, Vaz Te tries his luck with a great shot from outside the box and Cech has to make a good save.
Cole wins a corner on the left in the final minute of regular time this half. Two minutes of stoppage time will be added.
Carroll shoulder barges his way out of the West Ham box to give the visitors a bit of breathing room but Ba comes back yet again and prompts another save from Jaaskelainen.
Coming again, Ba pokes the ball through the legs of Demel to keep it in but Collins steps in to clear it away.
Jaaskelainen makes a fantastic save with his feet to deny Ba, who looks to be onto a sure thing. Lampard follows up with a shot from distance but it's wide.
Diame makes a great run all the way into the Blues' box and picks out Carroll, who tees him up with a return pass but his close-range shot is crucially blocked by Ramires.
Collins is there to head Mata's delivery away but Luiz meets his clearance with a sizzling left-footed volley which goes just wide again.
Hazard is fouled by Demel with a needless push and Chelsea have a free-kick on the left of goal, which Mata steps up to take.
Hazard shrugs off Reid and finds Moses near the edge of the area as Chelsea get forward again. Luiz squares a cross to Hazard and he tees up Mata but his curling shot is just wide.
There's a great chance for the Blues as Azpilicueta picks out Moses in the box and he turns to shoot but it's always going just wide.
Collins does well to hold up Hazard to subdue another Chelsea attack. On the ball again, he gets the better of Jarvis to threaten again down the right.
Jarvis wins Carroll's flick but is subdued by Azpilicueta, who does well to dissolve the danger. At the other end, Hazard prompts a relatively comfortable low save from Jaaskelainen.
Carroll and Cahill battle for the ball in midfield with the striker managing to keep it. A long O'Neill ball is then touched on by the frontman on the edge of the box.
Back on the ball, the Blues trade passes at the back in some more patient build-up, with Luiz slotting it to Hazard.
Play resumes as Ramires gets to his feet. He continues and does well to get a foot in to deny Carroll as he tries to build something.
Replays of Terry warming up earlier show he may have been winding up the Hammers fans after they gave him stick.
Ramires is clearly hurt after going down in a tussle with Diame for the ball as both players stretch for it. There's a lull in play as he receives treatment.
It's Luiz that does the honours and it's a low effort, slipping through the wall and troubling Jaaskelainen at the far post but he does enough to tuck it around.
Lampard is brought down by Diame on the edge of the box and it's a brilliant position for a free-kick for Chelsea. Luiz fancies it but it could be a Lampard special.
Carroll rises to greet a cross in the box and climbs above everyone to win it but his header isn't the best and he can't get it on target.
Vaz Te gets the ball away from Mata down the left. Collison finds Demel and he looks for Carroll with a long ball but its intercepted.
Chelsea are on the ball and hunting their second as Mata and Hazard team up again, patiently seeking a way through.
Azpilicueta gives a dodgy backpass to Cech and he's forced to clear quickly and send the ball straight out under pressure from Carroll.
Jarvis does tremendously well to track down a long ball and keeps it in to pick out Carroll in the box and he slots it home - but it's disallowed! The striker has been penalised for an apparent push on Luiz.
The Hammers are looking for a response but Diame fouls Ramires in the Blues' half and the hosts are back on the ball.
There was a sense of inevitability to that one. Hazard had troubled Jaaskelainen with a stinging shot seconds earlier and the ball eventually falls back to the Belgian, who produces a delicate chip into the box where Lampard is waiting on the six-yard line with the finishing header.
GOAL! LAMPARD GETS HIS 200th GOAL FOR CHELSEA! 1-0!
Play resumes as Hazard skips through midfield, gliding past Collison, and finds Cole, but his ball goes out off Vaz Te.
It's difficult to see what went wrong with Cahill, who wasn't under any challenge when he went down. It looks like he's going off...
Worrying for Chelsea as Cahill goes to ground in apparent pain. Terry starts to warm up to jeers from the Hammers fans.
The Blues win a free-kick after O'Neil bundles over Mata. Vaz Te heads it away but only as far as Mata again, but he can't get a shot away.
Chelsea win their first corner and in the aftermath Collins heads a ball straight at team-mate Jaaskelainen but the keeper makes an easy catch.
A great ball by Mata picks out Hazard on the charge and he slips it across for Ba in the box but he can't find the crucial final touch under pressure from the visiting defence.
Nothing comes of the Blues' break and West Ham are off again through Jarvis but his marauding run is held up by Azpilicueta and the Hammers take a quick free-kick in midfield.
O'Neill floats it in and Diame flicks it on to Reid but Chelsea intervene to go on the counter.
Former Hammer Lampard is getting some stick from the visiting fans whenever he touches the ball. At the other end, Carroll wins a corner for West Ham.
Azpilicueta sticks tight to Jarvis down the left to see the ball out. Diame finds O'Brien with the resulting throw but Ramires snatches possession.
Another foul on Carroll results in West Ham's second free-kick from range. Reid climbs to head it across the face of goal and Ramires clears but only as far as Collins, who comes close on the volley.
Collins looks for Carroll with a long ball but he can't quite win it. On a quick break, Lampard finds Ba with a great pass but the striker applies a less than stellar finish and it goes well wide.
Mata picks up the ball up again and plants another dangerous ball into the area but the onrushing Ba can't quite reach it with his leg at full stretch.
Hazard and Mata pair up, looking dangerous, as they try to break into the box but Reid is there to subdue the threat.
Chelsea's midfielders trade passes until Mata tries a long ball into the box, which is headed to safety by Collins.
A long Luiz ball is picked up by Demel and he keeps it in play but Lampard intercepts his run in the middle of the park. Hammers throw-in.
It's a disappointing effort from the Portuguese as his effort flies well over, high into the stands.
Luiz fouls Carroll to hand West Ham an early free-kick from range. Vaz Te steps up to take it...
Hazard slips an early ball into the box towards Ba after some good work from Mata but Jaaskelainen gets low to smother it.
It's Chelsea that get the derby underway, with David Luiz rolling the ball back to Petr Cech in the opening seconds.
Refereeing the clash today is Michael Oliver (Northumberland).
The teams are out on a damp afternoon in West London - but it's dry for the moment and it's almost time for kick-off. Enjoy the first half!
Not long until we get underway at Stamford Bridge. Thanks for all your feedback - keep it coming at half-time.
Hammers fan King Jones isn't getting his hopes up too high - "Last time when we beat CFC at home was one of the highlights of my season as a fan, i was over the moon. Thought if we could damage CFC then more big guns will fall. However i have had to change my stance of late, we just have not been solid and sharp enough in front of goal. So i don't expect anything for us from this game but will still be 100% behind the boys, this is the world of football and anything goes. Good luck HAMMERS."
@JoeHarbert241 tweeted - "supporting west ham today, as an arsenal fan. Think they can get something after Chelsea's battle in midweek! 0-1 collison."
Lee Gregory has been in touch to say - "Glad to see Mata starting. Backing him to score first. Going 2-0 Chelsea."
The Hammers, meanwhile, are 13th in the standings and nine points clear of the drop zone, but will be looking for some extra security with a result today.
The Blues head into the derby looking to cement their top-four prospects, currently sitting fourth and two points clear of Arsenal behind them.
Chelsea have won their last three Premier League home games, while they will be buoyed after turning around their UEFA Europa League tie with Steaua Bucharest in midweek to reach the quarter-finals.
West Ham haven't had the best of luck at Stamford Bridge in recent seasons, having failed to win there since September 2002 - a run they'll be keen to address today.
@JoshWaughman is pleased not to see Torres in that starting line-up - "Happy Torres isn't starting, he always scores against us. 3-1 West Ham, Carroll, Diame and Vaz Te. COYI."
@kingpinelvis96 has tweeted - "I think Chelsea will win today's game 4-0. Frank Lampard will score against his former club #easy."
Stuart Matthews is surprised to see Terry warming the bench once more - "Can't believe rafa has dropped terry again , going to be a tight game . Chelsea to just nick it 2-1."
The Hammers, who are seeking to become the first team to do a Premier League double over the Blues this term after winning the December meeting at Upton Park, make two changes from the side which beat Stoke, with Jack Collison and Ricardo Vaz Te starting.
Lamps is included as one of four changes to the Chelsea side that beat Steaua Bucharest on Thursday night, with Victor Moses, former Hammers striker Demba Ba and Gary Cahill included, while John Terry is on the bench again.
Frank Lampard makes Rafael Benitez's starting line-up this afternoon and the veteran midfielder is on the hunt for his 200th Chelsea goal against former club West Ham.
West Ham XI: Jaaskelainen, Demel, Reid (c), Collins, O'Brien, O'Neil, Diame, Collison, Jarvis, Vaz Te, Carroll. Subs: Spiegel, McCartney, Pogatetz, Tomkins, Taylor, C.Cole, Chamakh.
Chelsea XI: Cech, Azpilicueta, Luiz, Cahill, Cole, Ramires, Lampard (c), Mata, Moses, Hazard, Ba. Subs: Turnbull, Ivanovic, Bertrand, Terry, Mikel, Oscar, Torres.
Here come the teams then...
I'll be bringing you all the build-up ahead of kick-off at 4pm, with the team news coming shortly. In the mean time, why not drop me a line with your thoughts on the game. You can email firstname.lastname@example.org or Tweet me @SkySportsRachG.
A very good afternoon all and welcome to our live coverage of today's second London derby - Chelsea v West Ham.