"There's one player who's ahead of everyone else, who's in amazing form and who deserves all the praise. That player is Cristiano Ronaldo," said Casillas at an anti-bullying event on Tuesday.
"I don't think there's any doubt about it and he shows it game after game. It's good for Madrid because our hope is that, thanks to him, in a few months' time we'll be achieving our goals for this year."
Ronaldo has scored 17 goals in 14 league matches for Madrid this season.