The Italian praised the club skipper and defended Raphael Varane - who he says will one day be the best defender in the world
The goalkeeper has been the Italian's No.1 between the sticks in the Champions League, though Diego Lopez is being favoured in the first team for games in La Liga.
However, Casillas did himself a world of good with a top performance in Turin and the former Chelsea boss heralded the shot-stopper for his efforts in keeping the Bianconeri from scoring more than twice.
"He played a very good game," he told Canal Plus. "He was decisive and made two great saves in the first half.
"For him it is easy to not play every game, but he is ready to do it and that means he's very professional."
Raphael Varane was at fault for both Juve goals in the European encounter but the Italian trainer refused to criticise the Frenchman, who he clearly sees as having a brilliant future ahead of him.
"Varane is only 20 and will be the best in the world," he added. "I could not ask him to make zero mistakes."
Madrid looked off the pace in the first half but reacted to Arturo Vidal's 41-minute opener with second-half strikes from Cristiano Ronaldo and Gareth Bale, though Fernando Llorente equalised to earn the hosts a point.
Ancelotti continued: "We reacted so well in the second half. I'm very happy about this: the courage and the attitude.
"In the first half we defended too deep, allowing space to Paul Pogba and Claudio Marchisio. After that, we changed and pressed more in the midfield.
"Ramos was in the starting XI to cover gaps. Because in Madrid Juventus crossed too many balls in and Ramos is so good with the head. He played well, he is a great player but him at right-back is only temporary."
One more point in the final two group stage games - at home to second-placed Galatasaray and away to Copenhagen - for los Blancos will see them ease into the last 16.