Tennessee Titans wide receiver Rishard Matthews said on social media that he will quit the game if the NFL forces players to stand during the national anthem.
Matthews' stance came in response to a question via quitter that asked: "If NFL makes new rule on anthem will you still stay in locker room and face the fine/penalty?"
He responded with a tweet: "No I will be done playing football."
The posting has since been deleted from Matthews' Twitter account, although a screen shot of it was saved by Paul Kuharsky, a writer who covers the team.
Matthews is from a military family. His half-brother, who was killed in Afghanistan, served 10 years in the Marines and his father served 21 years in the Marines.
The protests by Matthews started following a torrent of criticism from President Donald Trump, who attacked players for not standing during the anthem.
NFL commissioner Roger Goodell sent a memo to each of the 32 teams earlier this week in a bid to end quell the controversy surrounding the players' protest.
Trump, via Twitter, inaccurately posted that Goodell's memo ordered the players to stand for the national anthem, which the league quickly rebuked.
The league and NFL Players Association issued a joint statement Wednesday in which it said the two sides will huddle during the upcoming league meetings.
"There has been no change in the current policy regarding the anthem. The agenda will be a continuation of how to make progress on the important social issues that players have vocalized," the statement read. "Everyone who is part of our NFL community has a tremendous respect for our country, our flag, our anthem and our military, and we are coming together to deal with these issues in a civil and constructive way."