The assistant coach to Spain boss Vicente del Bosque admitted that it was strange to see the Blancos captain and international goalkeeper on the bench on Saturday
Isco's opener and two second-half strikes from Roque Santa Cruz sealed the victory for the hosts in their 3-2 victory at La Rosaleda.
The 65-year-old believes that the Spain goalkeeper - displaced for the tussle with the now fourth-placed Liga side by back-up Antonio Adan - will feel shocked to have been omitted.
"Like everyone else, I found the decision very surprising," the Roja assistant coach to Vicente del Bosque told Canal+.
"I don't know the reasons, so I cannot say much more. A player of his experience does not need any reminders; just have a good season, there's nothing else one can say."
Mourinho's side now sit 16 points behind Barcelona in La Liga, and third in the race to retain their title.