Manchester United boss Louis van Gaal admits he dropped Juan Mata ahead of the derby for Marouane Fellaini.
United lost 1-0 at Manchester City, though Fellaini was United's outstanding outfield player on the day.
LvG said: "For me it is not difficult to have Wayne Rooney back. He is my captain and is very important to our team.
"Juan Mata was difficult to leave out but you have to choose - Marouane Fellaini has scored and given assists so he is important also.
"My philosophy is always the same. We want to dominate."
