Reports in Spain claim that Casillas is frustrated with boss Carlo Ancelotti at being dropped for Real’s Champions League game against Basel.
The 33 year-old is thought to be concerned about losing his place to summer signing Keylor Navas, who kept a clean sheet in the side’s 1-0 win in Switzerland.
And the reports claim that the Spain captain could look for an exit if the issue can be resolved by the end of January, putting Arsenal and Liverpool on red alert as they have been linked for some time.
This news will likely come as a blow to Manchester United as Real Madrid will step up their interest in fellow Spanish keeper David De Gea, should Casillas leave the Bernabeu.
By Phil Wellbrook