At the weekend the Red Devils broke Manchester City's winning run with a superb Premier League performance at the Etihad, winning 2-0 thanks to a penalty from Bruno Fernandes and a goal from Luke Shaw.
It wasn't all positive news from that game, though, as Rashford was forced off in the second half after rushing back to close down City winger Riyad Mahrez.
The England striker removed his boot and walked around the side of the pitch to the dugout with the physio.
Scans on Monday showed that there was no ligament damage to Rashford's ankle, but significant bruising means that he will not be fit enough for the Milan game, while there are doubts over his availability for the West Ham fixture, too.
The return of Edinson Cavani could be timely, then, as the Uruguayan missed the Man City game due to injury.
Should he make his comeback, he'll move into the centre-forward position with Anthony Martial likely taking Rashford's spot on the left.
Paul Pogba is still fighting to get fit following a thigh injury and his return date isn't really known as of yet, which will likely mean a central midfield pairing of Fred and Scott McTominay.
Shaw, along with Fernandes, has been Man Utd's best player this season and will continue at left-back, with Harry Maguire and Aaron Wan-Bissaka retaining their places from the weekend, too.
One change at the back might see Eric Bailly coming in for Victor Lindelof.
David de Gea is apparently still in Spain after the birth of his child so it will be another start for Dean Henderson.
Juan Mata and Phil Jones are definite absentees, while there are concerns over the fitness of Donny van de Beek.