Derby County chief executive Tom Glick insists they do not have to sell players after rejecting a bid from an un-named club for Jason Shackell.
Shackell, 28, has been a key player after joining from Barnsley last summer and played every game this season.
Glick told BBC Radio Derby: "It's no surprise we had a bid. It's nothing we accepted and nor are we interested.
"Jason is a player we want to keep and build around. We are not in a position where we need to sell."
Glick said they would only consider offers for non-fringe players if they felt they could replace them with players of equal or better ability.
"If we are in a position where we think we get offered a good deal and, importantly we have another player lined up who would be equally as good if not better, then that is always something we would consider," Glick added.
"That is how we are approaching this window.
"We have an interest in a number of our players and that's good because I don't know that we could have said that a year ago and certainly not two years ago.
"That's credit to Nigel and the job he and his recruitment team have done over the last couple of years.
"The good news is we have interest in our players. It's up to us to decide on each situation if that is of interest to us."
Several players are likely to be leaving Pride Park this summer, with Miles Addison and Lee Croft two who look certain to moving on.
"We have more players in the squad than we need right now," Glick added. "We have some players that we would be willing to part with if we the right offers came in so we are looking at all those situations."
Glick also said the Rams have identified where they want to strengthen in the close season.
He added: "What we know is that we want to get better at centre-forward, we need to do something wide right and we would like to look at some cover for Gareth Roberts at left-back - those are the priorities.
"We feel very good about the in-bound targets and are monitoring and acting day by day to make sure we are in a strong position in the market."
Glick also said the Rams were still hopeful of signing Northampton winger Michael Jacobs.
"He is a player we have watched extensively and we do like," Glick confirmed.