Washington receiver Terrelle Pryor said repeated racial slurs from Kansas City Chiefs fans prompted him to make an obscene gesture towards the crowd after his team's loss on Monday.
TV cameras caught Pryor angrily directing a middle-finger gesture towards the crowd at Arrowhead Stadium and he gave his side of the story in a post on Instagram.
Pryor said fans hurled racial slurs at him to the point that an NFL employee came to his side his side during the second quarter and stayed with him through the rest of the game.
Such treatment, Pryor wrote, in part, is "the exact reason why guys are kneeling during [the national] anthem."
He apologised to the Washington organisation and to his team-mates for making the gesture.
Pryor is in his first season in Washington after playing two years with the Cleveland Browns. The converted college quarterback has 13 receptions for 186 yards and a touchdown in four games.