The Spaniard has played in multiple roles in Mourinho's side this season and has proved to be a valuable utility player for his side.
The 27-year-old said: "It is not so easy to play for Manchester United, for example, as a No. 10.
"When you play for a big club, a No. 10 has to score 10 or 15 goals and make 10 or 15 assists, so it's not so easy. So I say to myself, if I want to play every game for Manchester United, which is my dream, I have to do something else for the club and for the manager.
"I think we have a good understanding between the manager and myself. We understand football the same way and we think the same; if you give everything, you are going to give things to the team. I can play at No. 6, No. 8 or No. 10. I have been asked a few times about it and I always say I don't have a preference because sometimes you perform better as a No. 6, sometimes it's better to be No. 8 and sometimes it's better to be No. 10.
"I just try to give solutions to the manager. He knows I can play at 6, 8 or 10. Even No. 2 — that I did against Everton at home.
"And if one day he wants me to play as a keeper, I will try my best. I think that's the right attitude and it's the attitude every Manchester United player has to have."