England boss Roy Hodgson has admitted that it will be difficult to persuade full internationals to drop down to the Under-21's to help young Lions secure European Championship qualification.
Under 21-boss Stuart Pearce is likely to ask for a number of senior squad members to play in a two-legged decider against Serbia next month, but Hodgson has said that no decision has been made.
He said: "I don't have hard and fast views. I will listen to Pearce's ideas and what he would like and make decisions accordingly.
"But there is no doubt once a player is playing regularly for the senior national team, it is never easy to suggest he should go back and play for the Under-21s."
Pearce is believed to want Alex Oxlade-Chamberlain, Jack Butland and Kyle Walker for the Serbia tie, with a decision to be made before October's World Cup qualifiers for the senior side.