David De Gea looks set to be given a chance to resurrect his Manchester United career after being included in Louis van Gaal’s Champions League squad – with compatriot Juan Mata backing him to remain professional.

The Spain goalkeeper has yet to feature for the Red Devils this season as manager Van Gaal said he was not in the right frame of mind to play while a transfer to Madrid remained a possibility.

But as the Spanish transfer deadline closed on Monday, an issue with paperwork meant a deal did not happen and it leaves De Gea at Old Trafford until January at least.

Should De Gea play in the group stage, he would be cup-tied should Madrid revive their interest in the winter transfer window as both clubs continue to blame one another for not getting a deal over the line.

He will be challenging fellow goalkeepers Sergio Romero and Sam Johnstone as United face PSV Eindhoven, CSKA Moscow and Wolfsburg on their return to European competition.

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Romero has been an ever-present so far for the Red Devils but, now De Gea will be at the club until at least the turn of the year, team-mate Mata has backed his fellow countryman to act professionally.

“He seems the same as ever to me, calm and relaxed,” said Mata ahead of Spain’s Euro 2016 qualifier against Slovakia on Saturday.

“It’s been a manic few days for him, he’s my friend and I’m there for him for whatever he needs. Right now he’s focused on the two upcoming games for the national team; being here will do him good and he’s going to be as professional as he has been throughout his career.

“His personality will help him. He manages to play even better in moments of maximum pressure and stress. His personality will help him on and off the pitch. His hunger and professionalism are intact. We all know what a great goalkeeper he is and he would make any team in the world better. The fans will get behind him and so will the team.”

Spain manager Vicente del Bosque earlier admitted it would be difficult for him to select De Gea in his European Championship squad for France if the goalkeeper remains on the sidelines at United.