Former Aston Villa defender Derek Mountfield fears they could lose Ron Vlaar this summer.
Mountfield admitted Vlaar's World Cup showings could come at a serious price for Villa, who are yet to open contract talks.
"The World Cup is a shop window," Mountfield told the Express & Star.
"Players like Ron Vlaar who have had an OK season with their clubs can suddenly meet up with their international team for a major tournament and get a new lease of life.
"Villa fans will like to see him doing well because it's always nice to see one of your own players performing at a World Cup. But they will also know that the better he plays the harder it will be for Villa to keep him.
"Hopefully he'll come back to Villa high in confidence, in good form, and he will sign a new long-term contract with Villa, but it might not be easy."
