Despite being continually overlooked, and even dropped from los Blancos matchday squad recently, Casillas insists both men are putting the club's interest first.
He said: "Our professional relationship is very respectful but on the personal side it is obvious that we don't have the same relationship.
"Xabi Alonso said the same thing and I don't think we need to keep going round in circles. I will say again, above everything is the club."
The 31-year-old also confirmed he is 100% fit and vowed to fight to win his place back from Lopez.
"I think it is obvious that I am OK to play," he continued. "I am always at the disposition of the manager and to try to help the team but someone else decides, not me.
"I am happy because for the past month my hand has been great and in the long run what I have to do is wait for my opportunity and take it when it comes.
"After three months without playing, I am like a kid wanting to make his debut.
"I won't desist for one moment. It is good for Diego Lopez because I will push him and he won't relax. He has had very good performances. He has helped the team get to where it is."
Can Casillas and Mourinho survive together long-term? Give us your shout below...