This is the reason the game is level...

Full-blooded. Mane and Fred both go in strong and the United player comes off worst. It is an honest attempt to win the ball from both though. It warrants a yellow but nothing more.

Jermaine Jenas
Ex-Tottenham and Newcastle midfielder on BBC One

Roberto Firmino's touches in the last 15 minutes have been world class, he's a big reason why Liverpool are back in this game.

Simon Stone
BBC Sport at Old Trafford

I was lucky enough to be at Chorley on Friday night and I felt the same thing but it is days like these when it really hits home that there are no fans at grounds.

With the increased away allocation for FA Cup ties, four goals, both sides being ahead at different times and the certainty of someone having to win today, the atmosphere inside Old Trafford would have been superb.

It's just not the same.

That combination of Firmino and Salah is causing United all manner of problems. The Brazilian shows superb strength to hold of a challenge and then thread a pass that puts Salah in on goal. He has defenders tracking back and Henderson darting out but gets a shot away that the keeper saves.

At the moment, Liverpool look the only likely winner, but this game has swung a few times already.

United make their move. On comes Bruno Fernandes for Donny van de Beek. Fred is also introduced, with Greenwood going off.

Liverpool very much in ascendancy now. Every loose ball is being picked up by a man in turquoise.

Techno Kopite: Glad to see the goal drought end. More so to make United work for absolutely anything.

Shane O'Neill: If they take the goal kick long, they don’t concede. I hate this idiotic way of playing the ball out

Aditya Thakkar: The way we have been careless with possession in our own half, we were begging to concede! Absolutely poor

Liverpool send on Sadio Mane - getting the forward boys back together. Gini Wijnaldum departs, so Curtis Jones will drop back into midfield.

Jermaine Jenas
Ex-Tottenham and Newcastle midfielder on BBC One

What a game we've got!

They have definitely stepped it up in the last five minutes. They worked themselves up, it is a sloppy ball from Edinson Cavani but when Roberto Fimino comes to life in the final third, things happen for Liverpool. Its a great finish from M Salah.

Image source, Reuters

And now Liverpool have a spring in their step. Alexander-Arnold draws a good save from Henderson with an angled drive.

Oh, huge chance!

Thiago's chipped cross is nodded on by Firmino in the box and James Milner is in, after taking a gamble with his run. He has to take it first time and gets it all wrong, firing over from just a few yards out.

Simon Stone
BBC Sport at Old Trafford

I was in the process of writing that Manchester United needed to be careful when Mason Greenwood equalised because although they were enjoying good possession and creating chances, Liverpool looked very capable of increasing their lead.

That situation has been turned on its head and now Jurgen Klopp's side who are the ones who must watch themselves because they cannot afford to concede again.

Sadio Mane has been warming up. I would imagine it won't be long before he is introduced.

This is a real test for Liverpool. They'll have been lifted out of their recent funk a bit by that Salah opener, but United's comeback will have rocked them.

They need to start hurting the home side, which they haven't really done since their goal.

Amazing that the little brick wall at the bottom of the slope off the United pitch is still there. Marcus Rashford takes a tumble down it after a challenge with Fabinho, but is thankfully OK. Rashford seems to suggest the Liverpool man may have done something a bit devious, but I'm not sure the replay supports it.

Loser92: great finish by Marcus Rashford!

Josh Earl: excellent link-up from Greenwood & Rashford again!!

The Supreme Meme: I told you. We have to 1-0 down!