Real Madrid have taken the first steps in moves that will see goalkeeper Iker Casillas finally leave the club this summer after 18 years, sources have told ESPN FC.

Although Casillas has not yet begun negotiations with prospective new clubs, and a destination remains unknown, his representatives have already started discussions about the financial package he would receive on leaving the Bernabeu, sources say.

The expected exit would have huge implications for Manchester United, given Real Madrid's long-standing interest in United's Spanish goalkeeper David De Gea, and the fact that he has not yet renewed his deal at Old Trafford.

Sources in Spain say two things right now are certain: "The mood around Real is very much that Casillas will leave this summer" -- and that the European champions want De Gea as his direct replacement this summer.