Reading boss Nigel Adkins believes that it will take time for Luke Shaw to adjust to playing for Manchester United.
The teenage left-back moved from Southampton for around £30m earlier this summer, and Adkins, who gave the youngster his debut at St Mary's during his time as Saints boss, thinks that Shaw could take a while to adapt.
He told Sky Sports News: "When we had Luke, he played in the youth team and he couldn't last a full game, and gradually, he got to the stage where he could last a full 90 minutes of the intensity of the Premier League, it's the highest level.
"He's just been to the World Cup with England, he's probably had two weeks off to recover and he's just had an unbelievable move to Manchester United.
"So all these things are going on, not just physically, but mentally, and like any new player, you've got to adjust and I'm sure the manager will do everything to manage him and develop him."
Shaw accepted that he is not currently in peak condition following his return from the World Cup.