Former Real Madrid defender Roberto Carlos has called Iker Casillas "one of the greatest goalkeepers in the history of football".

Casillas has long been regarded as one of the best stoppers in Spanish history, but the veteran has come in for serious criticism in recent months.

The goalkeeper lost his regular place in Real Madrid's first XI last season, while he made a number of high-profile mistakes for his country at the World Cup this summer.

Carlos, however, has leapt to the defence of his former teammate.

"Iker is a club institution. He's spent 15 years wearing that shirt, won many trophies and achieved many successes," the Brazilian told AS.

"He's an idol and one of the greatest goalkeepers in the history of football. Fans might protest about some players. That's normal. But Casillas still has a lot to offer Madrid."

Carlos, who represented Los Blancos between 1996 and 2007, is currently in charge of Turkish side Sivasspor.