Lisandro Martinez had to leave the Argentina camp very early during the recent international break due to a hip problem, while Victor Lindelof sustained a leg injury playing for Sweden.
Lindelof's timeframe is less clear, but Martinez's problem is less serious than first feared, and he could return for the visit of Everton on Sunday.
Leny Yoro has been back in training with a debut for him on the horizon, while Harry Maguire is also making positive strides in his recovery from an ankle issue, but none are expected to feature here.
That means that to accommodate Amorim's new 3-4-3 system, Noussair Mazraoui and Jonny Evans are set to start again in the back three either side of Matthijs de Ligt, as they did against Ipswich Town on Sunday.
Amorim was given a boost ahead of his first game in charge, with both Tyrell Malacia and Luke Shaw available for selection for the first time this season, and while neither were fit enough to start at left wing-back, both could get some minutes here.
Manuel Ugarte and Kobbie Mainoo were not deemed to be fit enough to feature from the outset in the draw with Ipswich, but they will likely be kept in reserve ahead of the clash with Everton, so Casemiro and Christian Eriksen could start as the midfield pairing once more.
Marcus Rashford was the preferred option up front, meaning recent big-money signings Rasmus Hojlund and Joshua Zirkzee were left on the bench, so the striking duo will hope this fixture can provide them with a platform to impress the new manager, along with out-of-favour winger Antony.
Goalkeeper Andre Onana was never rested by former manager Erik ten Hag in cup competitions, but Amorim did often implement a rotation system with his goalkeepers at Sporting Lisbon, so Altay Bayindir could be in contention to start here.
One player who always features is captain Bruno Fernandes, and he has enjoyed this competition as a Man United player, contributing to 11 goals in 13 home Europa League appearances since joining the club in 2020.
Manchester United possible starting lineup:
Onana; Mazraoui, De Ligt, Evans; Amad, Casemiro, Eriksen, Shaw; Antony, Hojlund, Fernandes