United begin their defence of the trophy as we welcome Jaap Stam's promotion-chasing Royals to Old Trafford in the third round.
The Dutchman will forever be highly regarded by United having won the Treble with the club during his playing days and makes a first return to his old stamping ground as a coach.
Sir Alex Ferguson admitted than when he sold Stam to Lazio 2001, it was his biggest mistake as United boss and the former defensive titan is sure to receive a rapturous reception.
He was appointed as manager of the Berkshire side in the summer and has proved to be an inspired appointment in his first managerial job having steered the Royals to third place in the Championship and well in the mix for a return to the top flight (six points off the two automatic promotion places).
United edged past League One Sheffield United at this stage last year, en route to that never-to-be-forgotten, record-equalling twelfth FA Cup win as we came from behind to beat Palace in the Wembley final.
"I still follow United and will always love the club and its fans, but now I need to prepare my team to play against them so it will be different."
Jose Mourinho looks set to shuffle his pack after the hectic festive fixture schedule, with Wayne Rooney back in contention having missed those matches over Christmas and New Year with injury.
"Some players need a rest and others need to play so I trust them all and there will be changes.
"We have zero injuries, there are 27 players and no injuries.
"I know that if I change three or four players in my team, some will say that there is a risk.
"We can do that because Reading is a Championship team but they are in third in their league and are better than some Premier League teams, I think.
"There is only a risk if there is the wrong attitude from my players, with the wrong frame of mind.
"If the players have a good responsibility and the same desire they are showing every match, then we have a good chance to win even if I rest some players and give others a chance."
Sergio Romero will deputise in goal but Eric Bailly is unavailable, while Bastian Schweinsteiger and youngsters including Axel Tuanzebe and Tim Fosu-Mensah could also get minutes under their belts.
The visitors also have a near fully fit squad at their disposal, with only Stephen Quinn and Deniss Rakels sidelined.
There will be a couple of familiar faces in the Reading ranks with former United pair Paul McShane and Tyler Blackett in their side.
Form guide: United W W W W W W Reading L W L W W W
Match odds: United 2/9 Draw 5/1 Reading 12/1
Referee: Andre Marriner