Birmingham City manager Lee Clark has claimed that clubs will have to pay a "substantial figure" if they want to sign goalkeeper Jack Butland.
The Blues rejected a £6m bid from Southampton for the England Under-21 international over the summer.
"By the time the window opens he'll have played 25 or so Championship games," Clark is quoted as saying by The Mirror.
"We would be looking for an even more substantial figure than we were offered in the summer – even though I certainly don't want it to come to that.
"Ultimately, it's down to the board. He's the future and the type of player I'd rather build my team around."
Everton and Liverpool are understood to be the frontrunners to land the shotstopper.
