The Spanish international has struggled for regular football in the last couple of weeks due to Ancelotti's favoured 4-3-3 formation.
However, the Madrid manager has revealed that he is considering selecting Isco in place of Karim Benzema for the clash in Barcelona.
"This system gives us greater balance, with [Luka] Modric and [Angel] di María alongside Xabi Alonso," he told reporters at a press conference.
"Isco can play where Di María or Modric play, but he isn't as comfortable, and he can play as a false nine, as he did against Osasuna. Perhaps tomorrow he could play in Benzema's position."