The NFL Players Association have lodged an appeal against the six-game suspension handed out to Dallas Cowboys star Ezekiel Elliott.
The NFLPA said it was challenging Elliott's ban in order to "ensure that the NFL is held to its obligation of adhering to principles of industrial due process."
Elliott was suspended last week for violating the league's personal conduct policy following an allegation of domestic violence by a former girlfriend in July 2016.
The NFL said it had evidence that Elliott, who enjoyed a dazzling rookie season at running back for the Cowboys last year, had physically assaulted his ex-girlfriend Tiffany Thompson on "multiple occasions".
US reports have said Elliott's legal team will attempt to discredit Thompson's evidence, claiming she had threatened to "ruin his career".
Elliott has not spoken to the media since the ban but on Twitter said he was "surprised and disappointed" by the NFL's decision.
His representatives also issued a statement challenging the ban, saying the NFL had made "factual inaccuracies and erroneous conclusions", promising that "a slew of additional credible and controverting evidence" would come to light.
