The 22-year-old winger, who scored a penalty in England Under-21's 1-0 victory in Albania on Tuesday, asked for a move from Old Trafford just prior to the transfer deadline and is confident that, unlike many others who leave United, it would not be a step down in his career.
"This game was good for me in terms of being in the shop window, especially with Sven-Goran Eriksson watching," Greening said.
"But I have to go from Manchester United. I've told the gaffer, Alex Ferguson, that I want to play more often and I'm not getting the chance with my current club.
"There is no problem and he has agreed that if the right club comes in then I can go. I've got to look at playing week-in and week-out at this stage of my career.
"Manchester United have got fantastic players but because there is such quality it is not the end of the world if I move on. I know I am good enough to play in any other Premier League team."
Greening joined United from York three years ago and in this time has made 26 appearances in all competitions, 14 as substitute.
