Thanks for tuning in this evening. Stay with us for the full match report and all the reaction.
That's it - the final whistle blows and it's West Ham 1 Arsenal 3.
Taylor tries to plant a cross into the box where four team-mates are waiting but gets too much behind it and it goes behind.
Arsenal are hogging the ball in these dying minutes. Reid and Ramsey battle for it down the right and the Hammers man comes off better.
Jenkinson gets forward down the right but his cross, intended for Giroud, flies well off target.
Five extra minutes are added this half. Giroud comes close again from close range as Arsenal continue to apply pressure after a wonderful pass from Cazorla.
Mannone makes a terrific diving save to deny Taylor as he tries a quick-thinking shot from range.
...but they do as McCartney wins a late corner for the Hammers on the left, which Noble steps up again to take.
The visitors are still looking in control in these dying stages and in no hurry to give up possession.
Taylor earns himself a booking after bringing down Arteta.
Podolski makes way for Laurent Koscielny as Arsenal look to preserve their lead.
More pressure from the Gunners as Giroud wraps his foot around the ball but can't get his shot on target.
He's looked lively throughout and he's been rewarded with a goal after being set up by Walcott on the edge of the box, putting away a great left-footed shot into the top right-hand corner.
GOAL! CAZORLA FOR ARSENAL!
The Hammers make another change as goalscorer Diame is brought off for Carlton Cole, meaning returning Carroll will have to go the full 90 minutes.
Cazorla fires in yet another corner and Giroud gets his head to it but Jaaskelainen collects.
Another chance and another corner for Arsenal after Mertesacker turns in the box and scuffs his shot just wide, with Collins getting a touch.
There's some good build-up involving Walcott and Arsenal win another corner after Collins is forced to put it behind.
Nolan tries to make it 2-2 and comes close from inside the box but he can't keep his shot down. Disappointing from the midfielder.
Walcott does well on the counter-attack with a surging run down the right, demonstrating his pace before releasing a long shot which he plants decisively home. He's booked for his celebrations in the same manner as Diame.
WALCOTT GOAL! ARSENAL 2 WEST HAM 1!
It's Carroll there again with the vital clearance as the Gunners' corner is dealt with. Diame does well to get away down the left but fires his cross straight at Mertesacker in the box.
Reid heads Cazorla's corner clear but Arsenal come straight back, with Ramsey planting a cross in the box. Podolski wins another corner as his shot comes off Tomkins.
Taylor can't stop a Cazorla ball going behind and Arsenal get another corner as they turn up the heat.
Tomkins come on for the Hammers for Demel in their second change.
Podolski tries a shot but Jaaskelainen somehow scoops it around the post. Seconds earlier Arsenal had appealed for a penalty after an apparent foul on Ramsey but the ref didn't give anything.
Mertesacker appears to have picked up a knock for Arsenal while subduing Nolan and it looks like they'll make a change.
News has emerged that Vaz Te has suffered a suspected dislocated shoulder after falling awkwardly in that collision with Mannone.
Nolan gets a great chance, finding himself onside and in space in front of goal but he hesitates and is shut down by Mertesacker.
Cazorla charges forward to try and greet Podolski's cross but he's held up. At the other end the pressing of Nolan and Carroll prompts applause from the home crowd.
Santos concedes a throw down the right, which Demel lofts in for Taylor, but he can't get his cross into the box.
Cazorla escapes the West Ham defence and finds himself in space but his shot is off target and a chance goes begging.
Carroll gets forward again for the Hammers and Jenkinson deals with his ball into the box. Seconds later he latches onto another long ball but heads it wide, coming tantalisingly close.
Arteta and Cazorla manage to subdue Diame on the edge of the box. Arsenal break again and Walcott tries to set up Giroud with a backheel in the box but slightly overhits it.
Taylor takes a free-kick for the Hammers from distance but the Gunners backline manage to deal with it. Carroll flicks on Taylor as West Ham come again but he's held up in the box.
Worrying for the Hammers as Vaz Te is helped from the pitch. Play resumes after that lull with a Mannone free-kick.
There's a lull in play as Vaz Te continues to receive treatment and it looks like he's hurt his arm. Matthew Taylor comes off the bench in his place.
Gervinho makes way for Walcott after a disappointing evening.
Vaz Te charges towards goal and catches keeper Mannone, who has already grabbed the ball, but it's the Portuguese who's needing the most treatment.
The throw is flicked on to Jarvis by Carroll's header and he swivels on it but can't keep his shot down as it goes over the crossbar.
Vermaelen is forced to make an emergency clearance after a positive run from Demel and it's a Hammers throw.
The Hammers' defence deal with the set piece but the Gunners get on the ball again as Arteta and Cazorla exchange passes in midfield.
Collins knocks an Arteta ball behind for an Arsenal corner, which Cazorla steps up to take on the left.
Arsenal make a change as Gibbs comes off for Andre Santos, appearing injured.
Noble fires a ball into the box for Carroll but Mannone charges out to collect. Plenty of service to the forward so far in this half.
The balls falls to Nolan in the box after some great work from Diame as the Hammers apply the pressure but the flag is already up.
A great cross from Vaz Te wins the hosts another corner. Noble floats it in and Carroll rises to meet it but the Gunners defence hold firm.
Mannone does well to claim the ball with Carroll loitering in the box but Diame gets forward again, slipping through to Vaz Te.
A lengthy bout of Arsenal passing is shut down as Carroll intercepts a pass. Jarvis links up with Diame as the Hammers mount an attack but Nolan's ball into the box comes off the head of Ramsey.
Carroll and Arteta tussle and the latter wins a free-kick just inside the Hammers' half as Arsenal try to build something.
Gervinho sneaks forward on the counter-attack, looking for a way into the box, but Collins holds firm with the crucial clearance.
The Hammers win an early corner this half, which Noble takes. Mannone is there to palm it clear and takes a slight push for a free-kick.
Play resumes at Upton Park as the hosts get us started this half. Jenkinson shuts down Jarvis on the left of the Arsenal end.
Thanks for your comments. It's almost time to get back underway - enjoy the second half.
Mr Potato Head has written in - "Amazing from The Hammers but i think arsenal were too good at the end of thefirst half 3-1 arsenal for me."
@scottluke1 tweeted - "Arsenal are unlucky not to be ahead. Would like to see a sneaky Hammers win though."
James Self has written in - "Decent from both teams but if Arsenal play like they did after they scored, they can maybe snatch a 2-1 win."
What did you think of that half? You can drop me a line at email@example.com or tweet me @SkySportsRachG.
The whistle blows for half-time and it's West Ham 1 Arsenal 1 at the break, with Diame and Giroud getting on the scoresheet.
The resulting free-kick sees Carroll flick the ball on for Nolan but the midfielder can't quite latch onto it and his effort goes wide.
Gervinho sees yellow after he's adjudged to have fouled Noble.
Two extra minutes are added this half. Vaz Te battles with Jenkinson on the break and the Arsenal defender holds him off until his team-mates can get back up the pitch.
Arteta does well to win the ball for Ramsey but the Arsenal attack is halted as a well-timed Collins' challenge closes them down.
Gibbs' long ball falls to no-one and trickles behind as it goes back to Jaaskelainen. Vermaelen wins it ahead of Carroll as Arsenal reclaim possession.
Good timing for the Gunners' equaliser just before the break. They're looking for another as they win a throw down the right, which Jenkinson takes.
It's a great goal and you can't say the Gunners don't deserve it. Podolski curls a tidy cross in from the left towards the Frenchman as he slides into the box ahead of Collins and sticks out a leg to poke it home.
GOAL! GIROUD GETS HIS FIRST PREMIER LEAGUE GOAL FOR ARSENAL! 1-1!
Collins steps up to take a Hammers free-kick inside their own half but Mertesacker is there to get to it before Carroll can in the box.
Ramsey tries to pick out the onrushing Jenkinson down the right but the defender can't quite keep it in play as West Ham win a throw.
Carroll is there again to clear with his head as he deals with Gibbs' long diagonal free-kick, then sees off another long ball from the defender seconds later. He's been central to attack and defence for West Ham so far.
Reid earns a yellow after running into Cazorla. It looks a harsh one but it's a free-kick for Arsenal just inside the Hammers' half.
Mertesacker very nearly finds Giroud with a flick-on into the box but he can't quite get his head underneath it.
Arsenal win a corner as Demel is forced to put the ball behind. Cazorla's effort is dealt with by Collins and flicked on by Jarvis.
Carroll tries to break but is held up by Podolski as the visitors win back the ball. Gibbs tries a cross from the left but it's dealt with by Jarvis.
Mannone gets caught by Carroll as he charges to meet another ball and Arsenal are given some relief as they're awarded a free-kick.
Bafflingly the Gunners defence allow Carroll a free header and it's only the hands of Mannone that keep him out.
West Ham win their first corner, which Noble steps up to take for the hosts, with Carroll loitering in the box.
Arsenal are forced to hold firm with some tight defending after Collins fires in for Carroll but the Gunners eventually win the ball for an infringement.
Noble releases Jarvis with a long ball and then goes to ground as Giroud comes in with a challenge but again nothing is given, and it looks like the right call.
Wenger is not happy with that challenge but referee Dowd does not give the second yellow and Arsenal have to make do with a free-kick just inside the Hammers' half.
Goalscorer Diame, already booked, charges in with a late tackle on Arteta and Arsenal are calling for his sending off.
Collins lofts a long ball upfield but it's seized by Gunners keeper Mannone. Seconds later, Mertesacker makes a well-anticipated run to deal with a Diame ball.
Ramsey tries his luck with a long range shot after some more good build-up play but his effort is well wide of its target.
Jenkinson tries to pick someone out with a cross into the box but Reid is there with the clearance to hand Arsenal a throw.
Mertesacker attempts to slot the ball through to one of his team-mates but the Hammers close down his pass. The Upton Park faithful have suddenly become much more lively.
The goal was against the run of play but well-executed by the hosts and now they've got their noses in front. Arsenal win the ball inside their own half as they search for a response.
Diame does brilliantly with a wonderful finish from an awkward angle after weaving his way past Ramsey to get his shot away. He earns a yellow for his celebration after going into the crowd.
DIAME GOAL FOR WEST HAM! 1-0!
Arsenal are on the ball again in midfield but Ramsey's cross in from the right is intercepted by Demel.
The Hammers defence are put under some serious pressure as Arsenal pile forward to greet the second corner but Carroll is there to head Giroud's effort clear, then denies Cazorla from the third.
A lapse in communication between Cazorla and Arteta sees the two collide but Arsenal win a corner, which is put behind by Collins for another.
Giroud chips a cross into the box from the left, looking for Gervinho, but Reid is there with the headed clearance.
Noble steps up for free-kick duty. Reid gets forward to greet it but can't turn it home under pressure from the Gunners defence.
The Hammers try to build from deep inside their own half, with Reid eventually lifting a long ball up for Carroll. The forward wins a free-kick after tussling with Vermaelen to win it.
Carroll wins a long Jaaskelainen kick but there's no-one there to pick up his header. On the break, Podolski charges off down the left for Arsenal.
Mertesacker is unhappy, claiming a handball after battling with Carroll, but the referee is unmoved. Diame concedes a throw in the Arsenal half.
There's some neat work from Ramsey as he skips forward down the left but there's just too much behind his cross and he tries to pick someone out in the box.
Gervinho loses the ball just inside the West Ham half but the visitors soon snatch it back. Mertesacker feeds it back into midfield.
Gibbs and Podolski link up down the left again, trying to build something. The Gunners look comfortable in possession in midfield.
Arteta chips a ball towards the box which Gervinho manages to keep in play. The Gunners have shown some good movement in these early minutes.
Jaaskelainen lofts another long ball upfield, looking for Carroll but it goes back to the visitors.
Vaz Te releases Jarvis to break on the counter-attack but Jenkinson is there to intervene. Carroll charges to meet a long ball but the Gunners' defence hold firm on the edge of the box.
The long ball is dealt with by Mertesacker and then Arteta. Podolski plants a cross in from the left after some nice build-up from the Gunners and Cazorla latches onto it but can't find his target.
Nolan breaks up a spell of Arsenal passing after getting away from Cazorla in midfield and West Ham win a free-kick inside their own half, which Collins steps up to take.
Arsenal are still on the ball as Ramsey and Cazorla trade passes, trying to find a way through but they're forced to drop back deeper.
Ramsey finds Giroud with a looping long ball from midfield and the Gunners win a throw down the left. Cazorla slips through to Gibbs who fires the ball into the box but Collins clears. Arsenal have started brightly.
Giroud and Cazorla link up, looking for a way through. The former tries an early shot, still looking for his elusive first Premier League goal, but prompts an early diving save from Jaaskelainen.
We're underway in East London and it's the Gunners that get things started but Noble snatches the ball in midfield, looking for Vaz Te.
Former West Ham man John Bond is saluted with a minute's applause following his death, while the home side are wearing black armbands.
The teams are out at Upton Park and we'll be getting underway very shortly. Enjoy the first half guys and keep your feedback coming at the break.
Zain from Milton Keynes has a lot riding on this one - "Arsenal better win today or else I'll be £500 poorer."
Gabriel Sutton admits it's a tricky one to call - "I've thought a bit about this game and I'm having a tough time calling it. Last week, Arsenal took a massive step backwards in terms of the title race and in giving away two easy goals from simple set pieces- it was back to the same old Arsenal. I remember Allardyce seemed to enjoy managing against Arsenal with Bolton and his West Ham side taking quite a direct, high-tempo approach, I think they could cause Arsenal's defence problems. If you bear in mind this is a derby game as well, that West Ham are above Arsenal in the table and that it's played at Upton Park, I think a draw is the best shout."
@rugbyfan15 tweeted - "Carroll back for hammers, makes us tick. 2-1 west ham- carroll, nolan and the ox for the gunners! #COYI"
Just a bit of background on this one - Arsenal have made a bright start to the season but suffered their first Premier League defeat against Chelsea last weekend, while the Hammers are unbeaten in four and currently sit a place above the Gunners in seventh in the table.
Our furthest-flung fan so far, Liam from Ardcroney, Ireland, says - "Hoping Arsenal are too strong for the hammers today - 2 -1 - Giroud and Cazorla."
Curtis Smith wrote in - "It will be a tough opening 45 minutes but arsenal I think will win comftebly 3-0."
Calvin Rawstron says - "Hi I think the score will be 1-1 both goods teams. But can be strong at home so I'm going with a draw."
Ant, the Gooner from Portsmouth, has written in to say - "Fancy us to the 3 points today and carry on our very good away form in the league so far. Seem to play with more freedom and confidence away from the Emirates and am going for a 3-1 away win with Giroud grabbing his first goal as think he may well start today."
Let's hear what you've had to say ahead of kick-off at 5.30pm...
On refereeing duty this evening is Phil Dowd (Staffordshire).
Arsenal boss Arsene Wenger makes three changes from his side's 3-1 Champions League win over Olympiakos on Tuesday, with German centre-half Per Mertesacker back after recovering from a virus while Aaron Ramsey and Olivier Giroud are recalled.
The only other change for the Hammers comes in defence, with George McCartney replacing the injured Joey O'Brien.
The obvious big news is that Andy Carroll is back in Big Sam's starting XI for the derby after fully recovering from a hamstring injury.
Here come the teams then...
I'll be bringing you the team news and all the build up very shortly but first why not get in touch and let me know your thoughts ahead of kick-off? You can tweet me @SkySportsRachG or email firstname.lastname@example.org.
A very good afternoon all and welcome to our live text commentary of the London derby at Upton Park between West Ham and Arsenal.