Louis van Gaal has said he is willing to drop captain Wayne Rooney if it improves the balance of his side.
The Dutchman has only omitted Rooney once this season -- when he was rested as a second-string side lost to MK Dons in the Capital One Cup -- and the four other games the 29-year-old has missed have been because of injury and a three-match suspension.
And Van Gaal said the versatility that has allowed Rooney to play as a striker and a midfielder this season counts in his favour -- but warned he is prepared to leave his joint-top scorer out.
"I need balance in the team. I'm looking for the balance," Van Gaal told MUTV.
"I hope to perform better because then the game shall be more attractive. I don't know if I shall use him always because it's also dependable of the form of the strikers.
"He's also a very good striker so I can use him on different positions and I like that because I like multi-functional players. I normally buy more multi-functional players than specialists."
Rooney has adapted to a deeper role in recent weeks, playing as one of three central midfielders in Van Gaal's 3-5-2 formation.
He has still scored eight Premier League goals and, unlike players such as Radamel Falcao and Juan Mata, is yet to begin a game on the bench under Van Gaal.
The 63-year-old has given United debuts to young defenders Tyler Blackett and Paddy McNair this season and said he hopes to develop a youthful side.
He added: "I want to work with young people. It keeps you young and you can make a team out of it. Now we are still building up and in the process."