The former Arsenal captain welcomes the role - even if it means he will not be breaking any goalscoring records.
"I'm not a player who will score 30 goals in a season and fight for the 'Pichichi' (the golden boot award in La Liga). Far from it," said the 25-year-old.
"I am a midfielder but it's true that in the past few seasons I've scored many goals, and when I play in advanced positions I try to do that.
"But when I play deeper I try to hold the position and work for others, get the team moving and if there is an opportunity to try to get a goal as well, but that's not what the boss is asking of me.
"I have to do what the coach asks me to and that isn't to score two goals every game. I try to do my job and I'm very calm, very content and very happy to be here.
"What I want is to stay and play at Barca and work as hard as I can."