What you need to know:
- Philippe Albert's stunning lob over Peter Schmeichel capped a memorable victory as Kevin Keegan's men, who also scored through Darren Peacock, David Ginola, Les Ferdinand and Alan Shearer, thrashed their title rivals.
Manchester United suffered their heaviest ever Old Trafford defeat against Liverpool as Jurgen Klopp's side romped to a stunning 5-0 win on Sunday.
Mohamed Salah scored a hat-trick, while Naby Keita and Diogo Jota also netted for the rampant visitors.
After one of the darkest days in United's history, AFP Sports look at some of their other nightmare Premier League defeats:
Newcastle 5 Manchester United 0, 1996
-- Philippe Albert's stunning lob over Peter Schmeichel capped a memorable victory as Kevin Keegan's men, who also scored through Darren Peacock, David Ginola, Les Ferdinand and Alan Shearer, thrashed their title rivals.
Southampton 6 Manchester United 3, 1996
-- Just a week after losing 5-0 to Newcastle, United crashed again, with Egil Ostenstad's hat-trick, an Eyal Berkovic brace and Matt Le Tissier's gem capitalising on Roy Keane's red card.
Chelsea 5 Manchester United 0, 1999
-- Gus Poyet scored after just 27 seconds, triggering a Blue day for United in west London, with Chris Sutton, Jody Morris, another Poyet strike and a Henning Berg own goal completing the visitors' humiliation after Nicky Butt's dismissal.
Manchester United 1 Liverpool 4, 2009
-- Fernando Torres ran riot, with Steven Gerrard, Fabio Aurelio and Andrea Dossena also on target and Nemanja Vidic dismissed for United, who survived the onslaught well enough to beat the Reds in the title race.
Manchester United 1 Manchester City 6, 2011
-- This was the first time United had conceded six goals at Old Trafford since 1930, their heaviest home defeat for 56 years triggered by doubles for Mario Balotelli and Edin Dzeko, as well as strike each by Sergio Aguero and David Silva.
Manchester United 1 Tottenham 6, 2020
-- United went in front courtesy of a Bruno Fernandes penalty inside the opening two minutes, but Anthony Martial's dismissal was the signal for Son Heung-min and Harry Kane to score twice, while Tanguy Ndombele and Serge Aurier also netted as Jose Mourinho enjoyed a memorable return to his former club.