Clubs have to confirm their squads to UEFA on Monday.
As he is battling to overcome a chronic bowel condition, there was some doubt as to whether Fletcher would be part of Manchester United's latest European assault.
However, after another encouraging outing for United's Under-21 side against Tottenham on Wednesday night, it is looking more likely Fletcher will be able to complete a successful return to first-team duties.
And with places available due to the number of home-grown players in Ferguson's squad, Fletcher is set to make the cut.
"We haven't finalised the Champions League squad yet - we're looking at that at the moment," said Ferguson.
"But Darren comes into the 25-man squad quite easily, without me having to leave others out because we have a number of players who we don't need to register because of the time they've spent with us as an Academy player.
"That's an advantage."
Ferguson also confirmed the 28-year-old will again link up with the Scotland squad next week as a further part of his rehabilitation programme.
And whilst he is wary of placing any timescale on the player's potential return to senior action for United, evidently the signs are hugely encouraging.
"Darren's put a lot of weight back on," said Ferguson.
"He's back to his normal weight from two or three years ago.
"He's training well every day and played really well the other night for the Under-21s.
"With the condition he has, it's a case of wait and see.
"But if he keeps doing as well as he's doing then obviously he'll be under consideration because he's a fantastic player."