All of Liverpool’s four FA Cup wins over United have been by a one-goal margin.
The last two occasions Liverpool have beaten United they have gone on to reach the final. In 2006 they lifted the trophy, 2012 they lost in the final.
They are the only Reds successes in the last 10 FA Cup ties between them.
Liverpool have won five of the last 35 visits to Old Trafford in league and cup, the last 3-0 in 2014 (only Jordan Henderson is still at Anfield).
There has been no win in seven visits since (four draws, three defeats).
This will be the second time since 1985 they have faced top-flight opponents in the opening two rounds.
A win today will see Liverpool reach the fifth round for the second time under Jurgen Klopp, last season being the first.
Ole Gunnar Solskjaer lifted this trophy twice as a player with United in 1999 and 2004.
He scored the winner against Liverpool in this round on this day 22 years ago, just nine minutes after coming off the bench.
United, a goal down to Michael Owen’s third-minute opener, equalised on 88 through Dwight Yorke before Solskjaer’s 90th-minute decider.
Craig Pawson was in charge of Liverpool in the third round at Aston Villa.
He has reffed this fixture twice, with Liverpool winning at Anfield in January 2020 after losing at Old Trafford in 2018.
This season’s scorers
Man United: Fernandes 15, Rashford 14, Cavani 5, Martial 5, McTominay 4, Pogba 4, Greenwood 3, James 2, Mata 2, own goals 2, Lindelof 1, Maguire 1, Van de Beek 1, Wan Bissaka 1
Liverpool: Salah 17, Jota 9, Mane 9, Firmino 5, Minamino 4, Jones 3, own goals 3, Wijnaldum 2, Grujic 1, Henderson 1, Matip 1, Origi 1, Robertson 1, Shaqiri 1, Van Dijk 1
* Statistics courtesy of LFC statistician Ged Rea (@ged0407).