Casillas believes Zidane’s legacy at the Santiago Bernabeu will not be sullied regardless of the outcome of the La Liga title race and insists that the Frenchman should not be blamed for everything.
After resigning from his post in the wake of winning three consecutive Champions League trophies, Zidane returned towards the end of the 2018/2019 season to manage Los Blancos, following a poor run under Julen Lopetegui and Santiago Solari.
The Frenchman steadied the ship and finished third in the league with Real before going on to win the title the following season.
Real Madrid risk losing their crown as Spanish champions if local rivals Atletico Madrid win their last game on Sunday but the former Porto goalkeeper believes Zidane should be immune from criticism.
"Zidane can't be criticised for anything," Casillas told Marca.
"What he has achieved is incredible, and is only in the reach of very few or even a single person."
Zidane and Real Madrid will be facing Villarreal in the final match of the season on Sunday.
Zidane’s side will have to win and hope Diego Simeone’s men slip at the José Zorrilla Stadium when they face Real Valladolid.
