Who's won what?
United have won 72 of their 139 games against Leicester.
The Foxes have triumphed only 36 times, with 31 draws.
The Red Devils have come out on top in the last four contests - including once apiece this season in the Prem and EFL Cup.
Amorim admits 'hard to turn things around'
Ruben Amorim has not even tried to downplay the size of his tasking in reviving the Red Devils.
Last Sunday's 2-0 home loss to Crystal Palace rammed home United's old Trafford's woes.
And Amorim's men have now lost 11 of their 24 Prem games.
So this evening's FA Cup clash might bring some relief.
But Amorim admitted: "It’s a moment that is hard to turn things around in a few games.
"It’s going to be like that, really hard until the end of the season.
"We want a different thing in our team and we want different profiles."
"We can improve our team, we will have time to train because I was always complaining about the [lack of] time to train. So now, we have time to train, we are going to improve."
Ruud departed United... with 3-0 win over the Foxes!
Ruud van Nistelrooy's successful spell as United interim boss ended on November 11 - the day after a thumping 3-0 win over Leicester.
Three weeks later, the Foxes appointed the former Netherlands hitman as their own permanent boss.
But since then not much has changed for both teams, results wise.
The Foxes are in the Prem drop zone while United are only five places higher in 13th place.