Isco, 25, has been subject to major debate over the past week after scoring an incredible hat-trick in the 6-1 thrashing of Argentina last Tuesday - despite arriving at La Roja short of regular game-time.
The playmaker has often been considered as a 'luxury' option by Zidane due to his lack of defensive work-rate and has been sacrificed with Los Blancos moving towards a more conventional 4-4-2 formation last month.
"Maybe with the national team Isco is different because he has eight matches with them [in a season], whereas here there are 60," Zidane told reporters, as quoted by Marca. "Here we play every three days.
"For me there are no backups. I have 25 very good players and I am going to use them all.
"There are moments in which some will play more."
Isco has scored seven goals and registered as many assists in 40 games across all competitions this season.