Mourinho has already dropped Wayne Rooney to the substitutes bench this season and would not be averse to leaving the likes of Paul Pogba or Zlatan Ibrahimovic out of his starting eleven.
Both players, who were brought to Old Trafford in the summer, have been criticised for some of their recent performances, and Mourinho has hinted that he is ready to make changes to his side on Thursday.
United are in the middle of a very busy period as they drew 0-0 at Liverpool on Monday and face a trip to Chelsea on Sunday before taking on Manchester City in the Capital One Cup next Wednesday.
Mourinho is ready to rotate his squad, saying: “Untouchable in our team has to be the spirit, the pride, the commitment to the club, the respect to the fans – that has to be untouchable, not players.
“I don’t want to give you the team (for the game against Fenerbahce), honestly.
“Wayne Rooney is working well – he’s one of the big responsible people for the atmosphere that the players can breathe because he’s positive and a good example. We count on him, to start or be on the bench. He will be there.”
United are unbeaten in five matches in all competitions and are 5/1 to beat Fenerbahce 1-0 with Rooney 8/5 to score at any time in the match.
Former United and Arsenal striker Robin van Persie now plies his trade for the Turkish side and is 10/3 to score at any time on Thursday.
Meanwhile, Timothy Fosu-Mensah has signed a new contract which will keep him at Old Trafford until June 2020, with the option to extend the deal for a further year.
The 18-year-old has made 12 first-team appearances for United.