Only Arsenal (13) have lifted the famous cup on more occasions than United (12), with at least one of the sides reaching the final in each of the last five seasons.
With the teams well out of the Premier League title race and seemingly competing for a top-four spot, the FA Cup has taken on added importance this season.
Ahead of this latest high-profile tussle between the English heavyweights, Sports Mole selects the strongest combined XI from both teams using only the players expected to be available for selection.
The easiest selection decision comes between the sticks as, following a disappointing World Cup and slow start to the season, David de Gea has returned to his best form and showed against Tottenham Hotspur earlier this month just why he is considered the best goalkeeper in the world. Bernd Leno has taken time to adapt to the Premier League, as did De Gea eight years ago, and the German still has work to do if he is to replicate the success of De Gea - or indeed Petr Cech, the man he has succeeded as Arsenal's first choice.
Bellerin would usually be the go-to choice at right-back, but the Spaniard is out for the rest of the season with a knee injury. There is a serious lack of choices in that area of the field, with a number of ageing players to choose from, though Diogo Dalot has at least shown some promising signs when given a chance. The summer signing had another impressive match against Brighton & Hove Albion when added to the starting lineup at the last minute, setting up his side's second goal, and should be given a regular run under Ole Gunnar Solskjaer. It is a similar problem on the opposite flank, meanwhile, with Luke Shaw the standout candidate.
The lack of quality central defenders perhaps explains why these two sides have struggled so badly for the majority of 2018-19. Unai Emery, not helped by injuries and suspensions, has been unable to settle on a centre-back pairing - or indeed a regular formation. United have also chopped and changed between a number of players, including the likes of Smalling, Phil Jones, Rojo, Victor Lindelof and Eric Bailly, but the latter two boast the most natural quality of that quintet. While not always at his best, Lindelof has looked a lot better since Solskjaer came in and Bailly also impressed before picking up a needless red card to cost him his place in the side.
Using a diamond formation in midfield allows us to cram in Paul Pogba, Lucas Torreira and Aaron Ramsey in a formation that should suit all three players. Torreira has been one of the signings of the season in the holding midfield position for Arsenal, producing 52 tackles and combining that with 1,165 passes. Pogba, meanwhile, has improved vastly since returning to United's starting lineup, scoring five goals and setting up four more in his last six matches. Another player who thrives in a box-to-box role is Ramsey, who showed against Chelsea just why so many of European football's heavyweight clubs are after his signature.
While his critics may point out that he misses far more chances than he takes, Pierre-Emerick Aubameyang is still joint-second in the Premier League scoring charts, netting 14 times in all - just two fewer than Alexandre Lacazette (8) and Romelu Lukaku (8) combined. Marcus Rashford is also on eight goals for the season, but the Englishman's form has vastly improved over the past month, with four of those goals coming in his last four matches, including the winner against Tottenham. Continuing with the theme of improving players, Anthony Martial is starting to frighten defenders again and would likely thrive in a system that allows him to drift across the final third.