Juan Mata has backed Manchester United and Spain teammate David de Gea to 'remain professional' following a difficult week for the young goalkeeper.

De Gea was involved in a long-running transfer saga with Real Madrid in the summer transfer window, and had looked certain to make the move to the Bernabeu on Monday evening.

The deal ultimately broke down after the official documents were not sent to La Liga in time, leaving De Gea in Manchester until at least January.

Mata, who is a close friend of the 24-year-old, has said that time away on international duty will be "good" for the stopper and has backed him to retain the support of the Man United fans.

"He seems to me the same as always, relaxed. It's been a hectic few days but he's my friend and I'll stand by him. It will be good for him to be here and only thinking about these two games. He'll be as professional as he has been throughout his career," Mata is quoted as saying by AS.

"This could help him. He is used to performing in stressful situations. It'll be good for him on and off the pitch. David is a professional and he will continue to be. He's a great keeper and any team would be better off for having him in it. The fans will be behind us all."

De Gea, who has not yet featured for Man United this season after his focus was questioned by Louis van Gaal, is reportedly open to signing a new long-term deal at Old Trafford.