They are constantly looking for ways to keep him stimulated, even considering switching to a 4-5-1 formation and using him as the spearhead to give him a fresh challenge.
Ferguson's tactic with his winning teams has always been to challenge the players to repeat their success, but it might not be that easy with Ronaldo.
After all, what do you give the player who has everything?
Although Ronaldo is content at home in the Cheshire countryside, Madrid is a better fit than Manchester for the boy from the sunshine island of Madeira.
United recognise that and are happy to let him make regular trips to see his new girlfriend, Spanish model Nereida Gallardo, in Mallorca and his family in Portugal.