Sanchez scores classy hat-trick
Carroll scores for first time this season
Gunners move up to second in table
West Ham one point above relegation zone
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I have to be honest, with Giroud having been used sparingly so far and now another injury; it begs the question! Where in the Premier League would Arsenal be without Sanchez?
Verallo of Cardiff
Image source, Getty ImagesWest Ham 0-1 Arsenal
Bradley Allen
Ex-QPR striker at London Stadium for BBC Radio London
This is a tricky time for Slaven Bilic, his first real test during his tenure at the Hammers.
What does he decide to do at half-time? Go for it, throw caution to the wind, take risks, but potentially expose yourself to the Arsenal counter-attack? Or continue to play cautiously and try and fashion something from a dead ball or late in the game? It's a dilemma.
Image source, PAWest Ham 0-1 Arsenal
West Ham have a late corner but Dimitri Payet's delivery won't be troubling anyone.
Arsenal go in 1-0 up at the break.
West Ham 0-1 Arsenal
Arsenal's Gabriel fell awkwardly while challenging for that ball and he's receiving treatment.
There's at least three minutes of injury time, so Francis Coquelin will fill in at right-back - ah, here comes Gabriel back on the pitch.
Image source, ReutersWest Ham 0-1 Arsenal
Arsenal really need to watch it.
Ashley Fletcher drops a ball into the Gunners area from the right flank and there's three West Ham players charging like Billy Goats Gruffs to slam a head on it.
It's Pedro Obiang who connects, but he nods it over.
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We have paid good money this year for at least 6 players who are well below the standard of the premiership. We have produced no one from the academy apart from Oxford - and he has rarely played since the first Arsenal game of last season. The board and the manager must admit the costly mistakes and sort out the squad for 2017. Losing Cresswell, Carroll, Ayew, and now Antonio is difficult but exposes very poor buying decisions in 2016.
Graham Clark (who first went to watch a game at Upton Park in 1950!)
West Ham 0-1 Arsenal
Dimitri Payet has a go from about 35 yards out.
It goes about 40 yards over the bar.
Enough said.
West Ham 0-1 Arsenal
Alex Oxlade-Chamberlain has come alive for Arsenal, as he gets to the by-line down the left and hangs a super cross in the air to the back post.
Theo Walcott didn't bust a gut to get in there though - it would have been a sitter if he had.
Image source, Getty ImagesWest Ham 0-1 Arsenal
Bradley Allen
Ex-QPR striker at London Stadium for BBC Radio London
I have sympathy with Slaven Bilic with his injury list, but a lot of Hammers supporters expect, especially in this new stadium, that the club's recruitment should be better.
There are huge squad concerns at West Ham, and the club really is in a rut.
Image source, ReutersWest Ham 0-1 Arsenal
Bradley Allen
Ex-QPR striker at London Stadium for BBC Radio London
Alexis Sanchez knows he's wasted that. He bursts through the West Ham back line and he was away. He angled across the shoulder of Ogbonna but Randolph closed him down well. It forced Sanchez to poke it round him and Reid did well to tidy it up.
Really, by now Arsenal should at the very least be two up.
West Ham 0-1 Arsenal
I take back what I said about Alexis Sanchez being potent - at least partly.
Alex Oxlade-Chamberlain slaloms through the middle of the West Ham midfield and into the opposition's half, before poking a through ball for Sanchez to chase - the Chilean pushes the ball too far past the onrushing Darren Randolph though and the chance goes a begging.
Have to agree with Tony Cocozza. Bilic's, or the Davids, signings have been very poor. Clear the confidence and squad from last season has been depleted and I don't see this team as being built with fighters. If we are to play our way out of trouble then Lanzini and Payet in particular need to pull their socks up....but with an unfit Carroll, a want away striker in Sakho, and Ayew and Zaza both on the bench where do the goals come from?
Anonymous
Remember to stick your names on your texts so we can give you credit!
Image source, Getty ImagesWest Ham 0-1 Arsenal
Alexis Sanchez and Mesut Ozil have been involved in 17 goals for Arsenal in the Premier League this season.
Sanchez - 8 goals, 4 assists. Ozil - 4 goals, 1 assist.
They've been a pretty potent pair.
#bbcfootball
Alan Ferguson: If ever a goal was coming it was that one. Arsenal been all over West Ham like a rash
James Harrison: Feghouli is a decent player, been unlucky with injuries and just hasn't been given a chance by Bilic.
West Ham 0-1 Arsenal
Spoooooooner!!!
Alex Oxlade-Chamberlain is released into the area for Arsenal - his shot is wonderful. Wonderful in the sense that it is awful.
He mis-hits it and it drifts towards the corner flag.
Alexis Sanchez has a better effort that Darren Randolph gets his body behind.
Image source, Getty ImagesWest Ham 0-1 Arsenal
West Ham don't look like they're ready to roll over and have their bellies tickled.
Some nice build-up play gets Alvaro Arbeloa in a good position down the right, but his cross is too deep.
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If West Ham don't buy big and get in tested Prem players in January we are doomed!
Pete Quilter
West Ham 0-1 Arsenal
Bradley Allen
Ex-QPR striker at London Stadium for BBC Radio London
Alexis Sanchez was bright as a button. The play out from Angelo Ogbonna was dreadful and Sanchez collected, advanced and then unselfishly laid it on a plate for his team-mate.
Mesut Ozil will never score an easier goal.
Image source, Getty Images
Mesut Ozil
After all Arsenal's work to create openings, West Ham go and do it for them.
Angelo Ogbonna dillies and dallies, dallies and dillies, and Francis Coquelin blocks his attempted pass from the back.
Alexis Sanchez picks up the loose ball, drives into the area and rolls a square ball to Mesut Ozil to tap in from a few yards out.
Image source, Getty ImagesWest Ham 0-0 Arsenal
West Ham's reshuffle means Dimitri Payet is now playing on the left of a four-man midfield.
It's a deeper role, but it he's already seeing more of the ball because of it.
The Hammers are looking like they've gotten to grips with the changes and settled down a bit.
Payet's done well to avoid getting a yellow card though, after a clumsy tackle on Francis Coquelin.