The Northern Ireland defender limped out of the Premier League game against Blackburn Rovers on Saturday after suffering a recurrence of an ankle injury.
The injury may mean that the 21-year-old could also miss out on the League Cup final next week against Tottenham Hotspur.
The former United youth player is to face a late fitness test on Wednesday before the Inter clash at the San Siro and until then it is not known whether he will take part in the game.
Speaking to TheManchester Evening News, Evans said, "It is a recurrence of the ankle injury I had before and is a bit tender. I caught it when I kicked the ground during the game.
"At this point, I don't know whether I will be fit for the San Siro. The doctor said he will have a look at it - and we will have a better picture then."
The 21-year-old's injury adds to manager Sir Alex Ferguson's list of unavailable defenders, with Gary Neville, Wes Brown, John O'Shea and Nemanja Vidic all set to miss out.
Ferguson was obviously annoyed with his growing injury list and admits he will find it hard as he keeps having to replace his defence.
"We are having a nightmare with defenders this season," commented Ferguson. "The defenders are being changed all the time. You reach a point when you start to find it hard."