De Gea was set for a move to Madrid on the final day of the Spanish transfer window this summer but a move collapsed due to late paperwork.
Keylor Navas has impressed for Madrid this term but it appears the Spanish club are still keen on a big name signing.
Courtois has endured a horrendous campaign with Chelsea and they sit 14th in the Premier League table.
Guus Hiddink’s side are likely to miss out on Champions League qualification and Courtois may be tempted into a move to the Bernabeu.
Any deal would be good news for Man United as De Gea has been in sensational form over the course of the campaign. That being said, it was clear that the Spaniard wanted to join Madrid and it would make sense for them to revive their interest.