Spanish media have insisted that De Gea has struggled to adapt to life in England and expect Madrid to launch a bid to sign the United keeper in January.
According to the Daily Mail, Real boss Jose Mourinho has a close working relationship with De Gea's agent Jorge Mendes and has sounded him out over a potential deal to bring the Spanish starlet back to his native land.
De Gea is currently in the midst of a fierce battle to tie down a place as United's first-choice keeper with Anders Lindegaard.
Sir Alex Ferguson has refused to give either man his backing as number one, forcing both players to fight for a starting spot.
The 21-year-old admitted during the summer that he has found adjusting to the Premier League more difficult than he expected due to the physical nature of English football.