Smalling's versatility has seen him play right-back and centre-back for United and England, but he wants to establish himself in the heart of defence for club and country.
"I've always been a centre-half, to be honest," he told the Sunday Mirror. "Obviously I've played right back and at the start of last season the only reason I played there was because we didn't have a right-back.
"But now that Rafael is playing there, I'm just looking to cement down a place at centre-half and I think that's where the manager has always seen me.
"I always think that if I'm fit I'm going to be in with a shout and I think the manager would put faith in me.
"Obviously when you're not fit other players have got to play, but when I'm fit and able to affect his decision, I'm confident I can do that."