Manchester United fullback Luke Shaw has accepted manager Louis van Gaal's criticism over his fitness.
The 19-year-old admitted he underestimated just how challenging it would be to make the step up from Southampton to Manchester United.
"Obviously I have seen that, and it's something I totally agree with," Shaw said when asked about Van Gaal's press conference comments.
"To play in this formation you have to be really fit. I am fit but I am not at the high level he demands.
"I have got to get fitter to get up and down (the wing). It's something I have got to work on."
