It has been claimed that Keylor Navas could start against Basel in the Champions League this week, but Ancelotti has hinted that Casillas is still his number one.
"The discussion of who our team's goalkeeper should be does not exist. I will not feed the debate going on in the media and online," he told reporters at a press conference.
"The debate is closed for me, I want to be clear on that. Debates on who should play for my team do not exist. I will never speak of which goalkeeper I play this season.
"Casillas has experience and character so he knows how to react to get through a situation like being whistled."
Costa Rica international Navas was signed from Levante this summer and enjoyed an impressive World Cup.