Luke Shaw has spoken candidly regarding his slow start at Manchester United, admitting he has not found it easy to adapt to life at the club following a high-profile switch from Southampton.

Having first emerged as a key transfer target for the club during the short-lived reign of David Moyes, left-back Shaw became the second signing of manager Louis van Gaal's first transfer window in charge when he moved to Old Trafford in a deal worth an initial £27m ($40m) in June 2014.

However, while the 19-year-old attracted great praise during his formative years on the south coast, he has endured a difficult debut season at Manchester United and injury problems have limited him to just 13 starts in the Premier League.

Shaw returned to first-team action on 18 April for the first time since being substituted at half-time of the FA Cup quarter-final defeat to Arsenal in March, featuring for 80 minutes at Stamford Bridge during a narrow 1-0 defeat to Chelsea before being replaced by Tyler Blackett.

"I am still young and coming to the biggest club in the world hasn't been easy for me. Hopefully, Saturday was the start for me coming back," he was quoted as saying by the Manchester Evening News.

"I wouldn't say it has been a hard three weeks, but it has been a three weeks that I have been able to learn a lot more about myself, so it has been a nice three weeks in that respect. I haven't been playing and there has been a lot of negative comments about me. It is something that isn't nice and I've tried to ignore it."

One accusation that has frequently been levelled at Shaw is that he just is not fit enough to start regularly for Manchester United. Indeed, Van Gaal himself even confirmed in the aftermath of the World Cup that the player needed to train individually in order to meet his expectations in that regard.

Those claims no longer appear relevant, though, with the England international obviously irritated by suggestions that his most recent absence was caused by a lack of conditioning.

"I saw a comment the other day saying I was taken off at half-time against Arsenal because I wasn't fit enough, but that's not true at all," he added.

"I know what the manager pulled me off for and it wasn't for my [overall] fitness because I could have carried on in the game. I spoke with the manager about it. I felt my back a little bit and he just wanted to be careful because I am young and hopefully have a long future ahead of me."

Defeat to Chelsea halted Manchester United's impressive record of six consecutive Premier League victories and they missed the opportunity to edge ahead of second-place Arsenal with manager Arsene Wenger's side on cup duty against Reading at Wembley.

They remain third prior to a trip to Everton on 26 April, although their advantage over rivals Manchester City was trimmed to just one point following the latter's comfortable victory over West Ham United.