The former Spain international has taken the time to discuss the goalkeeper's' situation and has urged La Roja's No.1 to remain patient
Casillas has been unable to displace Diego Lopez as first-choice shot-stopper ever since his return from injury, leading to plenty of controversy at the Santiago Bernabeu side as a number of players came to the 31-year-old's defence.
"As for Iker's situation, we could hardly expect it not to cause a massive stir," Buyo was quoted as saying by Marca.
"He is the best keeper or one of the best, but the circumstances are what they are and he suffered a bad injury.
"When he came back he was on form, but he came up against Diego Lopez, who's on fire. There's nothing strange about someone who's playing well keeping his place.
"Iker will have to wait for his chance, but that's the law of football and I'm sure he'll play again."
Buyo made over 300 Liga appearances for Madrid between 1986 and 1997.