Preston North End are trying to renegotiate a deal for Michael Hart, with the Aberdeen full-back unlikely to be fit for another six weeks.
Hart has already agreed to join the Championship strugglers in the summer, but Preston want to conclude a deal before the close of the transfer window.
However, the defender is carrying a hip injury which has sidelined him since Boxing Day and is expected to keep him out until March.
That has left an immediate transfer in the balance, with Preston boss Alan Irvine confirming talks with Aberdeen are ongoing.
"It's not completed," Irvine told the club's official website. "The reason is that the scan he had on Wednesday night has not shown the worst-case scenario by any means, but for an injury which looked like a recovery scale of anything from three to 12 weeks, it appears that his injury is one that will take six weeks to recover from.
"That obviously affects the fee a little bit - it's got to be based on that. If he was going to be out for 12 weeks we'd be saying 'there's no point in doing it now, let's do it at the end of the season', whereas if it was only three we'd have wanted to just do the deal now.
"We're looking for an adjustment in the current fee so that we can be compensated for taking a player who obviously can't play for a fair few weeks.
"It's probably better for everyone if we can just get it sorted and get him down here. I'm hopeful that's what will happen."