Is this a penalty? Anthony Elanga gets in down the right and has Nuno Tavares alongside him. There's leaning and arms involved. Elanga gets his shot away - which is saved - and then goes down.

No penalty on the field. VAR takes a long look... but decides no penalty off it, either.

Image source, Reuters

The Man Utd defence are all over the shop. A long ball forward is aimed for Eddie Nketiah, but despite a yard on the striker Raphael Varane boots the ball against Alex Telles and nearly gives up a chance.

Phil McNulty
BBC Sport chief football writer at Emirates Stadium

How can you defend like that off the back of a storm of criticism following the loss at Liverpool and with the stinging words of your manager ringing in your ears?

Nothing short of unforgivable - but Manchester United have had their chances since and have actually responded well to the setback up to now.

Image source, Reuters

You can clearly see the confidence coursing through this Arsenal team. Manchester United, much less so.

The visitors are grafting, though, shown through Cristiano Ronaldo tracking back to win the ball and end a Gunners attack.

Saka is back on and looks to be moving OK. Good news for the Gunners.

Aaron Ramsdale nearly blows it!

He boots a clearance straight to Bruno Fernandes, who is able to take a touch and then send in a shot that deflects wide.

The corner comes to nothing and Ramsdale breathes a huge sigh of relief.

Bukayo Saka is down. He clashed with Alex Telles and does not look happy.

Mikel Arteta takes the chance to get his players together to give some directions. He'll be concerned about his wide man, though.

Image source, Reuters

Like Liverpool fans before them, the Arsenal players applaud during the seventh minute as a mark of respect for Cristiano Ronaldo's loss.

Classy.

The home fans are in fine voice here.

They sense the chance to really rub salt into an old foe's wounds.

Another chance!

Scott McTominay gets his header to the United corner but his header lacks power and direction and bounces wide.

Chance for a leveller!

Anthony Elanga breaks clear of the Arsenal defence but his shot is pushed aside by Aaron Ramsdale.

Mark Schwarzer
Former Middlesbrough & Fulham keeper on BBC Radio 5 Live

It was a great save from De Gea; Man Utd have started so slowly. Arsenal, on the front foot, fully deserve to be in front.

The defending for the goal, though. Maybe Harry Maguire wasn't the only problem?

It took Liverpool five minutes to score against United midweek.

Arsenal have done it in two.

G: Am I the only one who is just thoroughly impressed that Cristiano has made himself available after what he's been through when so many players at the club simply cannot be bothered to turn up for games.

Bukayo Saka is straight into the contest, keeping the ball in and then weaving past a challenge. He is quickly taken out by Nemanja Matic.

Good lively atmosphere.

A place in the top four is the ultimate goal.

Two big clubs. It's highly unlikely both can make it into next season's Champions League.

We are under way.

There is a minute of applause before kick-off for ex-Arsenal scout Steve Rowley, who died on Sunday at the age of 63.

Mark Schwarzer
Former Middlesbrough & Fulham keeper on BBC Radio 5 Live

I think it is [Arsenal's game to win], the way they played against Chelsea I don't think many saw that performance and result coming. I think Arsenal need to continue that momentum and today is an unbelievable opportunity for them. Manchester United were very, very poor against Liverpool.