Doncaster have confirmed they turned down a "substantial" deadline-day bid from Birmingham for defender Matthew Mills.
The 22-year-old centre-half has attracted the interest of Championship rivals Birmingham, who are hoping to make an immediate return to the Premier League.
Blues boss Alex McLeish has been keeping tabs on the former Southampton trainee and watched him in Friday's 1-1 draw with Norwich.
But Doncaster were reluctant to let Mills go as they aim to avoid dropping straight back down following their promotion last season.
Chairman John Ryan insists Rovers are determined to not only maintain their Championship status but to ultimately challenge for promotion to the top flight so have no intention to sell their star players.
In a statement on the club's official website, Ryan said: "The rejection of the bid reaffirms the importance of Matthew Mills to Doncaster Rovers.
"Both the management and board feel that Matt is integral to the progress of the club. The club have had great interest in a number of our players, but the board and management want to build a side that can compete at the top of the Championship and beyond.
"We hope that the fans appreciate the level of commitment by the board to not make Doncaster Rovers football club a 'selling' club. We now hope that the fans come out to support the club and to back the board in their ambition."
Mills has made 61 league appearances for Doncaster, having two loan spells from Manchester City last season before joining the club on a permanent basis for £300,000 last summer.