According to Yorkshire Evening Post, the Whites are prepared to buy him out of his contract.
The 32-year-old shot stopper has 18 months left on his current deal with Real Madrid.
Casilla has not played for a while and he needs to leave the club in order to play more often. The Spaniard is Real Madrid’s third choice keeper behind the likes of Courtois and Navas.
The report claims that the player is set to fly to England next week for his medical. Casilla will be Leeds’ first January signing.
Leeds United could certainly use a quality keeper like him and Bielsa will be pleased to complete the move.