Several NFL stars have risked the wrath of Donald Trump by taking part in protests during the national anthem at pre-season games.
Franchise owners agreed on a policy earlier this year that requires players to stand for the Star-Spangled Banner if they are on the field.
On Thursday night in Philadelphia, Eagles stars Malcolm Jenkins and De'Vante Bausby raised their fists during the anthem, and Chris Long placed his arm around Jenkins' shoulder.
Jenkins said they "won't let (the league) stop what we stand for", adding: "I think it's important to utilise the platform as we can because for whatever reason, we have framed this demonstration in a negative light.
"Players have to defend why we feel the need to fight for everyday Americans, but we're doing the right thing."
In Miami, Dolphins receivers Kenny Stills and Albert Wilson were seen kneeling behind the rest of the line-up during the anthem, as teammate Robert Quinn raised his right fist.
Quinn said: "As a black man in this world, I've got an obligation to raise awareness. If no one wants to live in unity, that's why we're in the situation we're in."
And in Seattle, three Seahawks players – Branden Jackson, Quinton Jefferson and Duane Brown – ran into the dressing room ahead of the anthem being played and returned for the start of the match.
Their coach, Pete Carroll, said he supported any individual decisions over whether to protest.
Further protests took place in Jacksonville, where four players for the Jaguars also stayed in the dressing room.
Despite the demonstrations, an NFL spokesman said its policy on standing during the anthem had not changed.
Brian McCarthy added: "The NFL has been engaged in constructive discussions with the NFL Players Association regarding the anthem and issues of equality and social justice that are of concern to many Americans.
"While those discussions continue, the NFL has agreed to delay implementing or enforcing any club work rules that could result in players being disciplined for their conduct during the performance of the anthem.
"Meanwhile, there has been no change in the NFL's policy regarding the national anthem.
"The anthem will continue to be played before every game, and all player and non-player personnel on the field at that time are expected to stand during the presentation of the flag and performance of the anthem.
"Personnel who do not wish to do so can choose to remain in the locker room.
"We remain committed to working with the players to identify solutions and to continue making progress on important social issues affecting our communities."
More from US
The latest protests are likely to anger Donald Trump, who reignited his row with some of the sport's biggest stars when he cancelled a White House reception for the winners of the Super Bowl.
The US president has not yet commented on the pre-season demonstrations, which have been a feature of NFL games since Colin Kaepernick began to protest publicly against police brutality towards African-Americans.