Barnsley manager David Flitcroft will bid to pull off an unlikely upset against the club he closely followed with his mum and dad during the days when older brother Garry was City captain.
It is a tall order for the younger Flitcroft in only his 14th game in charge of Barnsley, and while the quarter-final clash does not pit the two brothers against each other - Garry is now manager of Chorley - the half-time entertainment at the Etihad Stadium will split the family in two.
"My sons Bobby and Billy are Barnsley mascots," David told Press Association Sport. "Garry's boys, Alfie and Tom, are City mascots and they're going to play in a game against each other at half-time.
"They're going to have a bit of a tear-up. My two have been doing their fitness work! They want to be ready for it.
"Bobby and Alfie are in the same class at school. Bobby in Barnsley colours and Alfie in Man City colours.
"We're looking forward to that."
It will be an emotional day for proud mum and grandmother Eileen.
Late husband John, with whom she travelled the length and breadth of the country to watch her sons play football, took his own life in 2008.
"It's a great game for mum," said David. "She spent a lot of time watching our Gaz and followed football a lot. We have a lot of good memories and she will be there on Saturday watching and supporting us. The phone call I wish I could make would obviously be to dad after the game. I've not got that now, but I don't look to the past anymore, I look to the future and this is a game for the future."