David De Gea named in Manchester United's Champions League squad

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 night, an issue with paperwork meant a deal did not happen and it leaves De Gea at Old Trafford until January at the earliest.

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 - with Victor Valdes missing out on the squad.

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.

"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."

Another name included in the squad is new signing Anthony Martial, as well as United's other five summer signings Romero, Matteo Darmian, Bastian Schweinsteiger, Morgan Schneiderlin and Memphis Depay.

The 19-year-old moved to Old Trafford from Monaco on transfer deadline day for an initial fee of £36million - making him the most expensive teenager in history.

Martial, who has linked up with the senior France squad for the first time having scored four times in 12 under-21 caps, adds much-needed competition to Van Gaal's attacking options but revealed he has not been assured of his preferred central role, a position currently occupied by United skipper Wayne Rooney.

"He (Van Gaal) asked me my preferred position," Martial said at a press conference ahead of France's clash with Portugal on Friday.

"I prefer to play in the centre but he told me I could play in a number of positions - it is the coach who decides but whatever position I play, I will do the best I can.

"Since I was young people have told me I have the right characteristics to play in England and I'm really keen to develop my game in the English (Premier League)."

Having scored 15 goals in 70 appearances for Monaco, Martial insists he is not concerning himself with his record-breaking price tag.

"I don't know if I'm worth 80million euros but I don't worry about the sums," he said.

"I'm going there for the football side of things, the price is between the two clubs and I don't see myself under any pressure."