Luke Shaw
Manchester United defender Luke Shaw has only started 12 Premier League games this seasonGetty

Manchester United summer signing Luke Shaw has admitted his debut season at Old Trafford has been a "frustrating one" that does not deserve more than a "C minus".

The 19-year-old left-back became the world's most expensive teenage footballer in the summer of 2014 when manager Louis van Gaal's side agreed to pay Southampton an initial fee of £27m, which could rise to £31m based on future successes.

The former Southampton starlet was expected to fill the void left by the summer departure of Patrice Evra to Juventus but he has so far failed to make the impact expected at Old Trafford due to a number of injuries.

Shaw has only started start 12 games this season while he has seen versatile Daley Blind excelling in his position during United's recent good run, having missed the last six Premier League victories.

The youngster is aware he is not fulfilling expectations but has hailed his decision to join United and hopes to overcome the situation in the near future.

"It's been frustrating one because of the injuries I've picked up but I'm loving it [at United]," Shaw said during an interview with Match Of The Day magazine. "If I was to write a school report on my first season here I'd give myself a C-.

"You don't realise just how big Man United is until you're actually here – it's frightening. It is the biggest club around.

"I'm playing with the likes of Wayne Rooney, Di Maria, Falcao and it's weird because my friends always talk about them, saying how good they are and I'm just thinking: 'Wow, I play with them!' I'm probably one of the luckiest 19-year-olds to be alive."

Meanwhile, Shaw has paid tribute to the sensational season goalkeeper David De Gea is having and hailed how the whole squad has helped him to adapt to life in Manchester.

"David De Gea is funny, he's kind, if you want to talk to him you can talk to him," Shaw said. "He's the nicest guy in football. He's been unbelievable for us this season and kept us in so many games, he's starting to become the best goalkeeper in the world," he said.

"We've got a few Spanish-speaking players and they're always playing their music and dancing around – the English lads hate it. Sometimes we can't understand them, they say stuff to us and we're like 'What?'

"Ashley Young is the joker in the dressing room. We still laugh about the time he got bird poo in his mouth against Swansea. If you ask him now, he'll say it wasn't bird poo. In the changing room we hung a fake bird above his place as a joke, which he didn't like."