Speaking of the situation, Pearson said: 'It is a situation that has been driven by him.
'In terms of confirming where he goes and for how much, I can't do that, but I would expect it to be resolved shortly.'
A fee being discussed by speculators claims a fee of around £1.4m is the amount agreed between the two clubs for the Under-21 England full back.
Rivals Nottingham Forest are also allegedly set to make a bid for Mattock.