The Spain international came within hours of swapping Old Trafford for the Bernabeu during the last window before a mix up with submitting the official paperwork scuppered the transfer.
Despite De Gea and Keylor Navas – who was set to move in the opposite direction as part of the deal – having agreed terms with the respective clubs, who had settled a fee, the forms needed to make the agreement official were not received by the necessary officials in time, forcing both players to stay put.
The United man has since penned a new contract – his previous deal was due to expire in 2016 – but a release clause of around £30m is thought to be in place, leaving the door ajar for a move to Real.
And reports claim that Los Blancos are ready to make a fresh move next year.
De Gea himself may be open to the idea of heading back to his homeland, with his family and long-term girlfriend, Edurne Garcia, living in Madrid.