Hello and welcome to our Manchester United v Arsenal liveblog. The winners will progress to the FA Cup semi-final but if United win, Piers Morgan will have to do a pretty terrible forfeit.

Guess we know who the neutrals will be supporting.

Here is the United team for tonight’s game.

And here is the Arsenal team.

If you are watching BBC tonight you are in for a treat – Roy Keane is on the panel with Alan Shearer.

2/1 that something like this happens.

Speaking of odds, if you are thinking of having a bet, United are 11/8, Arsenal are 2/1 and the draw is 12/5.

All is calm so far anyway.

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Wenger asked if he misses Fergie:

‘I’m happy to see him now… much more than before.’

The teams are out on the pitch now.

We are off at Old Trafford!

Alexis Sanchez cuts inside from the left and his shot is blocked well by Chris Smalling and cleared.

Ashley Young gets cynically taken down 30 yards out on the left by Bellerin, who gets booked. Free kick in a good position for the home side.

Rooney’s cross is headed clear and Arsenal look to break.

Corner for United after a run by Smalling.

Rooney gets a touch to Di Maria’s corner but the ball loops past everyone and Fellaini plays the ball back into midfield.

Arsenal have defended United’s crosses well so far and Sanchez has just won a corner for the visitors.

Nothing comes from the Arsenal corner and United look to launch an attack.

Mark Lawrenson criticising Ozil already.

Young gets fouled again high on the left. Bright start from the winger.

Szczesny gets a good punch to the ball and then Herrera gives it away trying to find Valencia on the right.

Fellaini gets the ball in space in the box but his attempt to turn goes badly wrong and Mertesacker clears. The Belgian should have done better there.

Rooney gets caught in possession on halfway and Cazorla breaks menacingly but his pass to Welbeck is too strong and DeGea gathers.

This was Fellaini’s chance earlier.
https://vine.co/v/OEQQgIQ0QeV

Bellarin goes on a run down the right wing and his cross is deflected over. However, the referee misses Blind’s touch and a goal kick is given.

Fellaini takes a ball down on his chest beautifully and tees up Young ten yards out but the winger slides for it and fires wide. Good chance.

Welbeck slides the ball into Oxlade-Chamberlain in space on the right wing but his cross is poor and misses everyone.

The Ox makes up for his earlier cross with a lovely run down the right that’s ended after a Rojo foul. Arsenal have a free kick on the edge of the area.

Ozil’s free kick is headed clear.

GOAL! Manchester United 0-1 Arsenal (Monreal)

The Ox buys a yard of space on the edge of the box with some excellent footwork and finds Monreal in space on the left. The fullback takes a touch and fires emphatically past DeGea to put the visitors in front.

After a wayward cross, Oxlade-Chamberlain has come into the game in a big way. He did very well to set up that goal.

GOAL! Manchester United 1-1 Arsenal (Rooney)

That didn’t take long! A Di Maria cross is guided past Szczesny by Wayne Rooney. A pinpoint assist by the Argentine winger.

Here was Arsenal’s opener that gave them the lead for about 30 seconds.
https://vine.co/v/OEQV1nzbOFi

Welbeck gets a bit of room in the box but his header isn’t strong enough to beat de Gea.

And here is the equaliser.
https://vine.co/v/OEQVxvJvQP6

Di Maria sells Valencia very short on the right wing and Monreal is able to nip in and clear.

Fellaini gets his head to a corner but can’t keep his effort down.

The ball is sticking to Fellaini regularly in the box but the Belgian’s touch hasn’t always been the sharpest.

Di Maria almost has a chance to get his shot away on the right wing but his first touch is poor and Monreal clears.

Szczesny gets down well to save a low shot from Di Maria, who stabbed the ball towards the net from a tight angle on the right.

Cazorla hits from a free from 30 yards out but de Gea saves comfortably.

Sanchez drives at the United defence and almost links up with Ozil but the German can’t get the ball under control on the edge of the box.

Half Time: Manchester United 1 – 1 Arsenal

Monreal fired Arsenal in front but a powerful Wayne Rooney header levelled the match moments later. Overall, it has been a very enjoyable game with a lot of chances at both ends. Hopefully we get more of the same in the second half.

Turns out that it’s Danny Murphy on commentary tonight. Am I the only one who thought it sounded like Mark Lawrenson?

SUB: Michael Carrick and Phil Jones are on for Herrera and Shaw.

We are back at Old Trafford!

Apologies there, it is Shaw who went off, not Rojo.

Rojo smashed into Oxlade-Chamberlain there and came away with the ball but his cross was too long. The Ox is down at the moment and may have to come off.

Fellaini plays in Di Maria outside the box but once again Monreal dispossess him. Besides his assist the Argentine has been poor tonight.

A Sanchez shot from the edge of the box takes a deflection but de Gea still claims it cleanly.

Not a lot has happened in the last few minutes as both sides struggle to create around the box.

Di Maria steals a yard on Monreal for once but drags his shot wide from the edge of the box.

GOAL! Manchester United 1-2 Arsenal (Welbeck)

Shocking mistake from Valencia as his weak back-pass is intercepted by Welbeck, who rounds de Gea and taps in. The striker didn’t mind celebrating against his old club either.

You really need to see Valencia’s back-pass to appreciate how poor it was…

Bellarin hauls down Young on the edge of the box and United have a free on the left wing.

Di Maria flicks a Rooney corner into the six-yard box and an unmarked Smalling wellies it high and wide. Very poor by the defender.

SUB: Callum Chambers is on for Bellarin, who was on a booking.

Here is Welbeck’s goal.
https://vine.co/v/OE2OtmIwJAF

Valencia fouls Sanchez and Arsenal have a free kick just outside the box on the left.

Sanchez’s dead-ball bounces right in front of de Gea but the Spaniard still manages to smother it.

SUB: Welbeck is off and Giroud is on.

A chipped cross by Sanchez is met on the volley by Cazorla ten yards out but de Gea does excellently to keep it out. That could have been game over.

RED CARD! Di Maria gets his second booking and is sent off as United trail 2-1. After getting a yellow for a bad tackle, the Argentine grabs referee Michael Oliver and gets another card.

Disaster for Man United. Is there any way back for them?

Chambers handles on the edge of the area and Man United have a free kick.

Rooney’s free is too high and doesn’t trouble the Arsenal goal

Here is the incident that saw Di Maria sent off.
https://vine.co/v/OE2n9qLBKOJ

United have five minutes to save their FA Cup campaign. Hard to remember a chance they’ve had in this half though.

Januzaj looks to get clipped in the box but Michael Oliver books the Belgian for diving. Looks to be a good decision on replay.

Sanchez almost seals it after getting played in by Cazorla but de Gea rushes out and clears. Five minutes added on here.

Arsenal look composed at the moment. Giroud wins a free on halfway.

A Carrick header almost lands at the feet of Smalling but Mertesacker clears before the defender can get a touch on the ball.

Ozil tees up Sanchez for an easy third but the Chilean takes a bit too much out of it and the ball clips the post and goes wide.

FT Manchester United 1-2 Arsenal

A deserved win for Arsenal as Danny Welbeck’s second half goal puts Arsenal into the FA Cup semi-final. The visitors took the lead after Monreal fired home following good play by Oxlade-Chamberlain but Wayne Rooney headed home an equaliser moments later.

Welbeck pounced on an errant back-pass from Antonio Valencia to score the winner for his side.

That is all for our liveblog tonight. Be sure to check the site in the next few minutes for more reaction to Arsenal’s win.