Postpublished at 14:32 Greenwich Mean Time 18 March 2017
That's it from me for the time being.
You can follow reaction to this game - plus coverage of the rest of Saturday's Premier League action - here.
Summary
Dawson heads West Brom opener from Chadli corner
Sanchez equalises with 22nd goal of season
Sub Robson-Kanu restores Baggies' lead a minute after coming on
Dawson scores his second with another header
Cech taken off injured, replaced by Ospina
Postpublished at 14:32 Greenwich Mean Time 18 March 2017
FULL-TIMEpublished at 90+3 mins
West Brom 3-1 Arsenal
A really good win for West Brom. Another crushing defeat for Arsenal.
What now Arsene?
Image source, Getty ImagesPostpublished at 14:20 Greenwich Mean Time 18 March 2017
West Brom 3-1 Arsenal
Kevin Kilbane
Former Republic of Ireland winger on 5 liveI've never seen this many "Wenger out" banners from this group of core travelling supporters.
It must be hurtful for him.
Image source, Getty ImagesPostpublished at 90+2 mins
West Brom 3-1 Arsenal
Arsenal corner. Nothing comes from it. That third goal destroyed any hope the Gunners had here. The Gunners have dug themselves out of some holes to finish in the top four in the past. This might be the deepest yet, though.
Image source, Getty ImagesPostpublished at 90 mins
West Brom 3-1 Arsenal
Late change for West Brom. They are bringing on a homegrown youth. He looks about 12 but Sam Field is in fact 18. He replaces Nacer Chadli.
'Groundhog Day'published at 14:18 Greenwich Mean Time 18 March 2017
West Brom 3-1 Arsenal
Kevin Kilbane
Former Republic of Ireland winger on 5 liveIt does feel a little like Groundhog Day.
They have had no pace anywhere at all and nothing from anyone from an attacking point of view today. They have been seriously lacking. Defensively they have allowed West Brom to just break them down.
I'm sure Arsene Wenger will make the point that one of the goals was scored with a questionable offside decision but I think referee Neil Swarbrick has made good decisions all game.
It will be interesting to see what Wenger says.
Postpublished at 87 mins
West Brom 3-1 Arsenal
Some Gunners fans have seen enough. One fan holds up a banner that reads 'Enough is enough'. It is all shaping up to be a sad and ugly end to one of the great managerial reigns.
Image source, Getty Images'No spark'published at 14:15 Greenwich Mean Time 18 March 2017
West Brom 3-1 Arsenal
Kevin Kilbane
Former Republic of Ireland winger on 5 liveI'm such a huge admirer of James McClean - he gives you so much on and off the ball.
There's just been no spark from Arsenal this afternoon.
Postpublished at 85 mins
West Brom 3-1 Arsenal
Arsenal are done. The fight has drained from them here. There could be some serious repercussions to this defeat.
Postpublished at 14:10 Greenwich Mean Time 18 March 2017
West Brom 3-1 Arsenal
Kevin Kilbane
Former Republic of Ireland winger on 5 liveAlexis Sanchez has just not been moving too freely at all.
Certainly seeing what we have seen in the second half, should Sanchez have been taken off in the first?
Image source, APSUBSTITUTIONpublished at 79 mins
West Brom 3-1 Arsenal
'You don't know what you're doing!' is the chant from the away fans as Alexis Sanchez departs to be replaced by Alex Iwobi.
Image source, Getty Images'Tremendous'published at 14:06 Greenwich Mean Time 18 March 2017
West Brom 3-1 Arsenal
Kevin Kilbane
Former Republic of Ireland winger on 5 liveWe've spoken about West Brom's strength from set pieces and Brunt coming off has not reduced that at all.
They have tremendous ability from set pieces. What's that? 14? 15 goals from corners the season now?
Outstanding.
Postpublished at 78 mins
West Brom 3-1 Arsenal
Tony 'Bomber' Brown
Former West Brom striker on BBC WM 95.6It doesn’t matter how you score goals. There’s nothing in the rule book to say you have to score goals in a certain way - you use the strengths in your team to score and that’s what Tony Pulis does, which is why they’re so good from set pieces.
Postpublished at 77 mins
West Brom 3-1 Arsenal
The 'Wenger Out' brigade are emboldened. The banners have been unfurled. The chants are starting.
Image source, AP
Dawson at the doublepublished at 76 mins
West Brom 3-1 Arsenal
Curtains for Arsenal. And they only have themselves to blame. It is another corner, swung again straight on to the head of Craig Dawson, who plants his effort firmly into the back of the net.
Yet again, where was the marking?!
GOAL - West Brom 3-1 Arsenalpublished at 74 mins
Craig Dawson
Image source, Getty ImagesSUBSTITUTIONpublished at 72 mins
West Brom 2-1 Arsenal
Off goes Chris Brunt, on comes Claudio Yacob.
Postpublished at 72 mins
West Brom 2-1 Arsenal
Neil Swarbrick is getting pressure from both sides here. He's had to deal with tackles on Sanchez all game, not he has to cope with boos from the home crowd, unhappy at what they feel is a foul on Robson-Kanu. He doesn't think it was. A few thousand vocally disagree.
Image source, Getty ImagesPostpublished at 70 mins
West Brom 2-1 Arsenal
Awful. Xhaka takes the free-kick but hits it straight into the wall. What a waste.
Postpublished at 69 mins
West Brom 2-1 Arsenal
Big chance for Arsenal. They have a free-kick 20 yards from goal. Granit Xhaka is over it...