Calderon also revealed how the deal was done during the recently completed season.
"Let's say that everyone involved in the operation agreed to do it this season," he told Five Live.
"That is what I can say. It has happened now, it was a bit early last season.
"I think it's going to be big event for Real Madrid, he is one of the best players in the world. He is going to help my former club get titles next season.
"Last season United decided not to do it because they thought it was too early and everyone agreed to do it this season.