The day after De Gea's move to the Spanish capital was called off, United and Madrid blamed each other for the collapse of the deal.
Madrid fired the first shot, issuing a statement on Tuesday afternoon which claimed delays at United's end had scuppered a deal worth £29million which would have also seen Keylor Navas head to Old Trafford.
United then hit back, claiming it was Madrid's fault the deal collapsed after they missed the deadline to register the deal with FIFA's Transfer Matching System (TMS).
A Red Devils statement read: "It is our understanding that the deals couldn't happen because: Real Madrid didn't upload David's documents onto TMS in time (Manchester United did), and Real Madrid didn't upload David's documents to the Spanish league in time, per reports it seems some 28 minutes after the deadline."
Senior sources at Old Trafford think Madrid president Florentino Perez may have had second thoughts about the deal after the club's fans expressed their dismay at the news that Navas was being used as part of the deal
In a poll of over 55,000 Real Madrid fans on the Spanish newspaper website Marca, nearly 89 per cent said they did not agree with the idea of swapping De Gea for Navas, who starred in the club's 5-0 over Real Betis on Saturday.
De Gea is currently on international duty with Spain, who play Slovakia and Macedonia over the next week
Once the international break is over, De Gea is expected back in Manchester.
Manager Louis van Gaal will attempt to reintegrate the goalkeeper back into the first-team squad.
The Dutchman has left De Gea out of his squad for the first six matches because he felt the player lacked focus, but United sources insist the pair have a decent working relationship.
The club have noted that De Gea has acted like a professional throughout this saga
He has turned up to matches and watched from the stands in his club suit, and has entered the dressing room for post-match team talks.
United's next match takes place a week on Saturday at home to Liverpool and Anthony Martial will be available for his debut against United's bitter rivals
The 19-year-old completed his record move to Old Trafford from Monaco on Tuesday.
After becoming the most expensive teenager in history, he is looking forward to the challenge of supplying the speed and creativity Van Gaal believes his team currently lacks.
''I don't feel the pressure,'' Martial told MUTV.
''I know there is pressure but I'm ready for it.
''I'm very proud
I'm very happy because I worked hard for this and my family is very happy about it."
Source : PA
Source: PA