The West Ham defender played with Darmian at Torino.
The Hammers are pushing for a Champions League place but an FA Cup win would also be massive for the club before they move out of Upton Park.
The Italian pair know each other from international duty with Italy and they played alongside each other at former club Torino.
Darmian has been speaking about facing up with his old pal to the official Manchester United website this week and he is clearly excited at the prospect:
"Yes, he (Ogbonna) is my friend. I played with him at Torino so off the pitch we are friends but on the pitch we are rivals.
"It was a difficult match, 0-0 at home, so we want to improve and beat West Ham. It was nice to see Angelo and he has told me he is very happy to play for West Ham, just like I am very happy to be at United.
"I spoke to him (after his goal v Liverpool) and texted him to say well done because it was his first goal and a very important one. But now it’s about us winning and getting to the next round."
Darmian has struggled for consistency since his move to England but Ogbonna has really come into his own in the past couple of months.
The lead defender at present due to several injuries in the West Ham ranks he has thrived under the pressure and will be hoping to keep Darmian and co at bay tomorrow afternoon.