Van der Sar has been attracting attention this season for some memorable performances. He was chiefly responsible for Coleman's team claiming a point in a goalless draw at Southampton with some great saves.
The former Juventus and Ajax keeper was in even better form when Fulham got the same result at Arsenal last year and Coleman knows he may not be able to hold on to him long-term.
He said: 'There is always a danger that you will lose your best players. I learned that with the Saha saga. If big clubs want your players badly enough then it is the same for us, Charlton and a lot of other clubs in our situation.
'There is not a lot you can do. You can fight to keep them like I did with Saha. But if they want them badly enough you might have to take it on the chin. I am not saying that is going to happen or that we are going to lose Edwin but it is a possibility for every club outside that top three.'
Fulham are likely to be without Alain Goma tonight because of a hamstring problem but Lee Clark should return after a calf injury.
Aston Villa have Gavin McCann suspended and Dion Dublin faces a late fitness test.
Fulham v Aston Villa, Loftus Road, tonight, 7.45pm
