Casillas was first called up to Real Madrid's senior team during a Champions League match against Rosenborg when he was aged 16 in November 1997.
Casillas ຖືກຮຽກຮ້ອງໃຫ້ເປັນທີມງານອາວຸໂສຂອງ Real Madrid ໃນລະຫວ່າງການແຂ່ງຂັນແຊມປ້ຽນລີກກັບ Rosenborg ເມື່ອເຂົາອາຍຸ 16 ໃນເດືອນພະຈິກ 1997.