And while there is no immediate end in sight to that situation, Ferguson has assured the Londoner he will eventually get the job on a full-time basis.
"The difference here is that I operate my captains on seniority.
"In the long-term Rio will be captain of Manchester United, there is no question about that. It is a position we are very comfortable with that.
"His leadership qualities have improved tremendously over the last couple of years and his ability is there for all to see."