Speaking in his first pre-match press conference since he replaced sacked head coach Ruben Amorim on Monday, Fletcher said the pair were fit and should be back in the squad after returning from injury.
Fernandes picked up a hamstring injury before Christmas while Mount was injured the day after. Both missed the 1-1 draw at Leeds United on Sunday although Fletcher said both had been pushing to play.
"They'll be on managed minutes and restricted minutes because they have only just returned to training so that is good news, especially because they are players who have been in good form," he said.
"To have them available for selection is obviously great news for me, the players and the club and the fans."
Former midfielder Fletcher, a United stalwart with 342 appearances for the club and most recently was coach of the under-18 squad, said he was focused on the Burnley game and not the longer term.
"I've had a conversation and the focus is on this game and then we'll speak after the game," he said of talks with the club.
"Honestly it is not something I've thought about. I'm focusing on Burnley. I think that discussion's for after the game.
"It's all happened so quickly, all my concentration and efforts and thoughts are going into Burnley. I know that sounds like a generic answer, but it is what it is."
Fletcher said it felt 'surreal' to be in charge.
"It is an amazing honour to be able to lead a Manchester United team, I didn't think it was in my wildest dreams that that was something that could potentially happen," he said.
"To lead out the team is an amazing honour and something I am really proud to do, not in the circumstances I expected it to happen, so that obviously is something that doesn't sit quite easy with me.
"But I have just to think I have a job to do and I've got to lead the team tomorrow and think of the great honour and pride in doing that."