The Seattle Seahawks and Tennessee Titans sat out the national anthem before Sunday's game in Nashville.
As a Marine Corps' colour guard stood at the 30-yard-line and game officials, cheerleaders and others stood for the anthem, the bulk of both sidelines remained empty. As soon as the song concluded, the Titans and Seahawks emerged from their locker rooms and headed for the field.
The Seahawks released a statement from their players about 30 minutes before kickoff at the Titans' Nissan Stadium saying the team would not participate in the anthem.
"As a team, we have decided we will not participate in the national anthem," the statement read. "We will not stand for the injustice that has plagued people of colour in this country.
"Out of love for our country and in honour of the sacrifices made on our behalf, we unite to oppose those that would deny our most basic freedoms. We remain committed in continuing to work towards equality and justice for all."
The Titans' statement read: "As a team, we wanted to be unified in our actions. The players jointly decided this was the best course of action. Our commitment to the military and our community is resolute and the absence of our team for the national anthem shouldn't be misconstrued as unpatriotic."
CBS Sports reported the NFL is not expected to issue fines to teams that stayed in the locker room during the anthem.
Seahawks players, led by Michael Bennett, have been outspoken in their support of the movement to protest police brutality started last year by then-San Francisco 49ers quarterback Colin Kaepernick.
The team and owner Pete Carroll released statements on Saturday supporting the players after President Donald Trump said at a rally on Friday and repeated on Twitter that those who kneel during the anthem should be "fired".
Earlier on Sunday, the Pittsburgh Steelers spent the national anthem in the locker room with the exception of U.S. Army veteran Alejandro Villanueva, who stood at the edge of the tunnel with his hand over his heart.