It was a dismal day for United boss Ole Gunnar Solskjaer, made all the worse by Paul Pogba's red card just 14 minutes after he had been introduced as a half-time substitute.
There were early signs, on Liverpool's first goal, that United's defenders might not be on their game.
The fact that this awful piece of defending could end up not being the worst piece of defending of the match says it all, really..— Michael Hindson (@mic_1987) October 24, 2021
Shaw, Maguire, AWB, absolute shambles..#MUNLIV #MUFC pic.twitter.com/wm3JtNU1WM
Just 45 minutes in, and former United defender Rio Ferdinand had seen enough.
We are always gonna pose a threat because of the individuals we have.....but we are so easy to play through it's unreal!— Rio Ferdinand (@rioferdy5) October 24, 2021
Embarrassing 1st half... men against boys! 🤬 #MUNLIV
It's fair to say that Man United tweeting "trailing at the break" was quite the understatement ...
And some supporters had seen enough by half-time and had already begun to make their way home.
Manchester United fans leaving Old Trafford at the half 😮 pic.twitter.com/ETWe7r9ObO— ESPN FC (@ESPNFC) October 24, 2021
Pogba came on at half-time. For a bit.
Solskjaer subbing Greenwood for Pogba may have two reasons. To spare Greenwood the embarrassment of enduring any more of this and ensuring that Pogba has to suffer with everyone else— Mark Ogden (@MarkOgden_) October 24, 2021
And ESPN's resident Frenchman Julien Laurens was certainly glad to see him.
45 minutes too late... pic.twitter.com/Quba6chlkR— Julien Laurens (@LaurensJulien) October 24, 2021
It didn't take Salah long to bag his third goal of the game ... and a piece of Premier League history.
History. Maker. 👏 pic.twitter.com/vvLmHugKJM— ESPN FC (@ESPNFC) October 24, 2021
Former Liverpool boss Kenny Dalglish was having one of the best days of his life. You can't say that for legendary United manager Sir Alex Ferguson ...
Sir. Kenny Dalglish V Sir. Alex Ferguson pic.twitter.com/F8oQUIRrG8— Barth Omaliko (@UncleBarth) October 24, 2021
Edinson Cavani has scored 423 goals in his career and is currently playing as a holding midfielder for Manchester United.— Richard Jolly (@RichJolly) October 24, 2021
Former Liverpool striker Robbie Fowler decided to stick the boot by suggesting Harvey Elliott, who is out long-term with an ankle injury, should be brought on in the second half.
Get Harvey Elliott on...on crutches @LFC— Robbie Fowler (@Robbie9Fowler) October 24, 2021
United super-fan Usain Bolt was in shock.
Wake me up when this is all over— Usain St. Leo Bolt (@usainbolt) October 24, 2021
And it doesn't get any worse than Liverpool fans sarcastically singing United's very own "Ole's at the wheel" chant.
If there's one thing we can guarantee, Liverpool will be rubbing this in on their social media accounts for days to come!
Even an opticians got in on the act.
If you're a United fan, we recommend bathing your eyes for ten minutes with cotton wool and then closing them for four years #MUNLIV— Specsavers (@Specsavers) October 24, 2021
Trent Alexander-Arnold is in no doubt about who the main man is.
Cristiano Ronaldo hasn't seen many days like this...
This is tied for the heaviest defeat of Cristiano Ronaldo's career 😟— ESPN FC (@ESPNFC) October 24, 2021
The only other 5-goal loss was in El Clasico 11 years ago. pic.twitter.com/RRDkmfSpO4
And if one person knew this was coming, it was David Brent.
Man Utd 0-5 Liverpool. Remember this tweet.— David Brent Music (@DavidBrentMovie) October 24, 2021