Iker Casillas has admitted that he left Real Madrid this summer because he "needed to breathe" following 15 years of service to the Spanish giants.

The Spaniard made over 700 first-team appearances for Real Madrid during a glittering career, but his relationship with the supporters turned sour in his final months.

Casillas departed the Spanish giants for Porto in July and the 34-year-old has said that he was desperate for change of scenery.

"It was a difficult change but it's an experience and I needed the feelings of excitement inside me," Marca has quoted the goalkeeper as saying. "The situation wasn't the best. I was always the focus of attention, both good and bad, and I needed to breathe. I'm happy now and I think it shows on my face."

Casillas won five league titles during his time in Spain, in addition to three Champions Leagues.