Doncaster are considering taking legal action after winger James Coppinger was left with a broken cheekbone following a challenge by Bristol City's Yannick Bolasie.
Referee Fred Graham let the challenge go unpunished in Bristol City's 2-1 win on Saturday.
Coppinger, however, will undergo surgery on the injury on Friday and is expected to miss the rest of season.
Doncaster chairman John Ryan told the club's official website: "I was disappointed that the referee did not take any action against the lad for the late challenge, but I have taken legal advice regarding this matter."
Rovers boss Dean Saunders added: "He's fractured his cheekbone and it's an absolutely outrageous head butt.
"It's right in front of me and the referee's not even spoken to the lad."