Porto have reportedly failed with their initial proposal to sign Real Madrid goalkeeper Iker Casillas.

It has been suggested that the 34-year-old, who has spent his entire career at the Bernabeu, has decided to leave Los Blancos amid speculation that they are keen to replace him with Manchester United's David de Gea.

Casillas has informed Porto that he would be open to the prospect of a move to the Estadio do Dragao, but they may have a problem matching the Spain international's wage demands, according to AS.

The report adds that during initial talks, the Dragons asked Madrid to continue to pay 100% of Casillas's earnings - something that was rejected by Los Blancos.

It is not known if the Primeira Liga outfit will return with a second offer.