Man Utd move up to 4th, Arsenal drop to 8th
Giroud smashes home in injury time
Rooney clips in second on counter-attack
Gibbs deflects Valencia shot into his own net
Keeper Szczesny taken off in second half
Oliver Zissman:, external I've never left the Emirates before the end until today. What a disgrace!
Joe Vidler:, external Thanks for the memories Wenger.
Seb Amann:, external I have no idea how Arsenal have lost this game. Absolute madness, they've been all over United.
Chris Bevan
BBC Sport at Emirates Stadium
"While the Manchester United fans celebrate noisily in one corner of the ground, many Arsenal fans are making their exit. There are banners being held up in front of me reading "enough is enough - Wenger out"."
One shot, two goals! That's the story of Manchester United's night. A clinically finished chance by Wayne Rooney though, and one that Danny Welbeck and Jack Wilshere could do with learning from.
Game over. A classic counter-attack as Arsenal are left with only Nacho Monreal back. Angel Di Maria sends Wayne Rooney away into the clear, the United captain takes his time and clips the ball over Emiliano Martinez. The away end erupts. Louis van Gall is off his seat, the Arsenal fans are out of the ground...
Image source, Getty ImagesBetter from Arsenal, they move it quickly and Santi Cazorla flashes the ball across the goal - but Tyler Blackett is stationed and clears his lines well. Watch and learn Kieran Gibbs!
Manchester United are eight minutes away from moving back into the top four. And about eight players away from winning the league.
DeathApeDisco:, external Klopp available next summer? Will there ever be a better candidate to succeed Wenger at the Emirates?
Inspiration:, external Arsene is a good coach no doubt but you can only be good for so long #aresenlneedschange.
Michael Peters:, external Arsenal out of the title race? Fair to say everyone is except Chelsea and maybe Southampton
Arsenal trying to thread a needle, intricate stuff on the edge of the box but United have seven back and Michael Carrick is able to make the block and clearance. Where's the plan b from the Gunners? They've not tested Tyler Blackett and Paddy McNair enough since going behind.
Image source, PASo Arsenal now have Danny Welbeck and Olivier Giroud up front, with Alexis Sanchez in the hole. Plenty of options.
Olivier Giroud is back, he's on for Aaron Ramsey. Can the big man have an instant impact?
Image source, PAMuhumuza Joseph:, external Calamitous own goal...calamitous season so far well out of the title race. Overhaul at the Emirates needed.
RAGreeneCNN:, external This is where #Arsenal show whether they deserve to be in the top four: Fight back, or roll over and die?
Irfan Ul Haq:, external And we have the Wenger bashers out yielding all the weapons! #WengerMustGo_NOT
James Wilson for Robin van Persie - it's a change we are getting used to seeing. It was said when Danny Welbeck left Old Trafford that Louis van Gaal saw Wilson as a better option. Can he show us all why?
I'd quite like to see that Timirlan...
Alexis Sanchez scored twice for Chile during the break, but he can't find the target on this occasion, curling a free-kick over the bar. Danny Welbeck is then stopped in his tracks by Chris Smalling. Good tackle.
Image source, PADave Payn:, external If Arsenal lose, well, you can only dine out on success for so long. Wenger's time surely up.
Vaishach:, external the last thing Man Utd will be hoping this season is for de Gea to be injured than those defenders. Sensational.
Timirlan Dzaurov:, external Bayern could easily take down these Arsenal and ManU sides... and I mean playing them both at once.
Marouane Fellaini heads a corner tamely wide. Manchester United are set up perfectly for the breakaway now, everyone back with Angel Di Maria ready to burst clear at pace. Arsenal will have their work cut out to find any space - but they do have a corner. Robin van Persie heads away.
Arsenal go direct, and to good effect. Danny Welbeck wins a header well, down to Santi Cazorla, and he rattles in a strike which David De Gea is again right behind.
Chris Bevan
BBC Sport at Emirates Stadium
"Interesting to note that Manchester United are ahead without having had a shot on target - that Antonio Valencia effort was heading wide before it hit Kieran Gibbs. One player who has not helped in that department is former Arsenal striker Robin van Persie, who has not had a single shot at goal tonight, and has barely had a touch of note either.
"All of that will not bother the Dutch striker, or his manager Louis van Gaal, if the score stays the same."
There are a lot of big players out there who have contributed very little to this game. They have 25 minutes to have an impact. Few groans of frustration in the Emirates as a patient move breaks down.
Tola:, external Man Utd winning without having a shot on target! Football Gods must be smiling haha.
Harvey Austin: , externalThis is a battle of who is worse. Wenger actually winning that one.
Jacob Bridgwater:, external Probably the most self-destructive force in the universe #poorarsenal
The very essence of 'taking one for the team.' Pure filth from Santi Cazorla to chop down Ashley Young. United were in on the counter attack and Cazorla is booked.