Ole Gunnar Solskjaer has a perfect record so far, Unai Emery has had a mixed start at Arsenal. The fans interviewed outside the ground were largely positive.

Thoughts?

It really was. So many huge games between the two sides...

Phil Neville
Ex-Man Utd and England defender on BBC Radio 5 live

In the 1990s you think of the intensity, the fights in the tunnels, the great goals. It was the biggest rivalry in Premier League history.

Ian Wright
Former Arsenal & England striker on Match of the Day

The way Arsenal played against Chelsea was encouraging, with Aaron Ramsey in the diamond role.

With Aubameyang and Lacazette up front, they're dangerous. But there’s not enough goals apart from those two.

Alan Shearer
Former England captain on BBC One

This is a very good opportunity for both clubs to get some silverware.

Both are giants of this competition, with 25 FA Cups between them, and both managers are doing very good jobs after coming into tough circumstances.

The clubs aren't quite the clubs they were. I still think this is the best chance of silverware for these clubs this season.

This is so punny it hurts

Guy Mowbray
Match of the Day commentator

Image source, Getty Images

The first mega-match of this season's FA Cup comes early, featuring the competition's best ever sides, whose previous clashes have provided some of its most iconic moments.

Alan Sunderland….Ryan Giggs….their joyous, sprinting celebrations - many of us don't need to YouTube search to 'see' them.

It really could be a tie to give us new memories too, with both sides full of confidence having shown in the last fortnight that they can beat fellow 'big guns'.

Yes, we'll enjoy the ongoing drama of their Premier League race for the top four, but you can't beat a game with instant jeopardy - the feature film version of a smash hit series.

Get the popcorn in.

Just in case you were wondering, Bristol City and Bolton Wanderers are also playing their fourth round tie tonight because Bristol Bears are taking on Exeter Chiefs at Ashton Gate tomorrow afternoon.

Image source, Getty Images

The Mogo: Difference in quality across the benches is marked tonight, Arsenal will need to start strong

You can follow all of the weekend's FA Cup action on bbcfootball's Instagram account, and keep an eye on their story for some behind the scenes extras

From Ryan Giggs' classic wonder goal to Patrick Vieira's cup-winning penalty in 2005 - watch 20 years of big moments between Arsenal and Manchester United in the FA Cup.

James, you've had a scheduling nightmare. Of epic proportions.

Dinner in the lounge?

James Lockwood: Sadly missing the @EmiratesFACup, external game tonight to have dinner with the in-laws...the struggles of married life! Hoping to return to see Ole has lost for once!

Alex Scott
Ex-Arsenal Ladies & England international

Seeing Arsenal's display against Chelsea was a reminder as to what they are capable of, and at the moment United are just playing so well - very attack-minded and full of energy.

It is a chance for Unai Emery's side to make a real statement by ending Ole Gunnar Solskjaer's winning start, and of course the FA Cup is a big opportunity for Arsenal to get a trophy this season.

There is so much history between the two sides too. I think we have got one of the most exciting games of the season coming up.

Image source, Getty Images

I understand why Arsenal fans are frustrated because they want to see new arrivals to help the team kick on - but I don't see the point in rushing and bringing in players for a short-term fix.

Join Gary and co live on BBC One or at the top of this page now...

Image source, Getty Images

It is FA Cup fourth-round weekend - a competition that started with 736 clubs is down to the final 32.

There are just four more hurdles to clear before the final, but who will make it to Wembley on 18 May?

Will Barnet, the last non-league club standing, make it through to the fifth round?

BBC Sport takes a look at five of this weekend's 16 ties.

Image source, Getty Images

Record 13-time winners Arsenal host 12-time champions Manchester United in the FA Cup fourth round tonight (19:55 GMT) - one of three ties live on BBC One and online over the weekend.

Championship side Millwall host Premier League club Everton on Saturday (17:30) and holders Chelsea face Championship Sheffield Wednesday on Sunday (18:00).

BBC Sport will cover all 16 round four ties on television, radio and online.

The draw for the fifth round is live on Monday's The One Show from 19:00.

David Ornstein
BBC Sport

Image source, Reuters

Arsenal are in talks to sign Paris St-Germain midfielder Christopher Nkunku.

The 21-year-old France youth international played under Gunners head coach Unai Emery when he was in charge of the French side last season.

But he has featured less frequently since Thomas Tuchel took charge.

Arsenal want to take Nkunku on loan until the end of the season with an option to then buy - but PSG are said to favour extending his contract before sanctioning a loan move.

Martin Keown
Former England defender on Radio 5 Live

With Ainsley Maitland-Niles playing at right back, I think Arsenal may play a 4-4-2. They played with almost twin strikers and Aaron Ramsey in between at Chelsea but I can't see that happening. The team is very flexible but i think they are a bit concerned about Maitland-Niles.

The defensive partnership has been unsure. Shkodran Mustafi is in and out of form, Laurent Koscielny coming back is key. Sokratis doesn't get the respect he deserves. Those two look the best Arsenal partnership.

Arsenal: Cech, Maitland-Niles, Papastathopoulos, Koscielny, Kolasinac, Torreira, Ramsey, Xhaka, Iwobi, Lacazette, Aubameyang. Subs: Elneny, Ozil, Lichtsteiner, Monreal, Leno, Mustafi, Guendouzi.

Man Utd: Romero, Young, Bailly, Lindelof, Shaw, Ander Herrera, Matic, Pogba, Lingard, Lukaku, Sanchez. Subs: Jones, Mata, Rashford, Martial, Grant, Fred, Dalot.

Referee: Craig Pawson (South Yorkshire)