World Cup winner Casillas was benched for Saturday’s 3-2 defeat at Malaga with 25-year-old understudy Antonio Adan stepping into the breach.
“I’m not used to being a backup, but above all I am a team player. The thing to do is to keep training and try to regain my place,” Casillas told La Sexta television.
“Mourinho didn’t say anything during the week, but we abide by the decision of the coach. I am feeling good, but the one who decides is the coach and I have to keep training to regain his confidence. We have a healthy competition for all the places.”
Mourinho, whose champions are 16 points behind leaders Barcelona, continued to insist on Sunday that he had been right to drop Casillas.
“I have a clear conscience. I try to have the best team for each match,” said the coach on arriving in Lisbon where he will spend the Christmas vacation.