Washington quarterback Dwayne Haskins issued an apology on Tuesday after images of him partying in a strip club without a mask emerged on social media.
In a statement on Twitter, Haskins admitted he had put team-mates at risk after breaching Covid-19 safety protocols.
"I want to publicly apologize for my actions this past Sunday," Haskins said on Twitter. "I spoke with Coach (Ron) Rivera yesterday and took full accountability for putting the team at risk.
"It was irresponsible and immature of me and I accept responsibility for my action.
"I also want to apologize for creating a distraction for my team during our playoff push. I will learn and grow from this and do what's best for the team moving forward."
Under safety protocols agreed between the National Football League and NFL Players Association before the season, players can be disciplined if they are found to have engaged in certain forbidden "high-risk" activities.
These include attending an indoor night club or bar with a crowd of more than 10 people and without wearing a mask, and attending a private gathering of more than 15 people without wearing a mask.
Images on Instagram showed Haskins sitting with a woman on his lap while both brandished handfuls of cash.
Haskins had played in Washington's 20-15 home defeat to the Seattle Seahawks earlier Sunday, filling in for the injured Alex Smith.
Washington remain on course for a playoff berth, despite winning only six games this season. They lead the NFC East with a 6-8 record, ahead of the Dallas Cowboys and New York Giants, who are both 5-9.