Alan Irvine has admitted that Nottingham Forest's offer for Paul McKenna was impossible to turn down.
McKenna spent 11 years at Deepdale and captained Preston last season as they finished in the Championship play-off zone.
He joined Forest earlier this summer after Preston accepted an offer of £750,000 for his services.
Irvine accepts that it was disappointing to see the midfielder leave but insists Preston could not afford to match the wages offered by Forest.
"We have lost both Simon Whaley and Paul McKenna this summer, with both of them representing the club on a number of occasions last season," Irvine told skysports.com.
"Paul McKenna was almost an ever-present and the club captain as well, so that was a huge blow, but it was hard for us to stand in his way.
"Nottingham Forest made a good offer, which we didn't want them to make, but one which we couldn't really refuse.
"He was a fantastic servant to this club and because of that we had to be fair to him and it was an opportunity for him to earn more money than we could pay him.
"We are short in midfield now because of those two departures and so bringing in a couple of midfielders was my main priority this summer."
Preston suffered play-off heartache against Sheffield United at the end of last season but Irvine expects his players to use those feelings to spur them on this term.
"They have to try and use that disappointing end to last season as determination to bounce back," he explained.
"Last season proved that we are a force in this division, despite not having the biggest squad or the biggest budget.
"We proved that with a tight, well-organised squad, which were strong mentally and had a very good team spirit that things can be achieved in this league.
"We are hoping to emulate that play-off finish this season."