The Dallas Cowboys players, staff and owner Jerry Jones took a knee before the US national anthem at Monday’s game against the Arizona Cardinals in a protest against President Donald Trump.
Boos were heard in the stadium before both teams stood and linked arms on their own sidelines for the anthem.
Trump said on Friday that NFL players who fail to stand during the national anthem should be sacked or suspended.
Jones was one of seven NFL owners to donate to Trump’s inauguration.
In widespread protests at the weekend, players responded by kneeling, linking arms or staying in the locker room.
Basketball star LeBron James praised the players who protested against Trump, and accused the US president of “using sports to try and divide us”.
James praised the players’ unity, and said: “The people run this country.
“I’m not going to let one individual, no matter their power, ever use sport as a platform to divide us.
“Sport is so amazing, what it can do for everyone. No matter the shape, size, weight, ethnicity, religion or whatever – people find teams, players and colours because of sport. It brings people together like none other.”
James, who plays for the Cleveland Cavaliers and has won three NBA championships, campaigned for Hillary Clinton, Trump’s rival, during the 2016 presidential election campaign.
How did we get here?
Quarterback Colin Kaepernick was one of the first players to kneel during the national anthem last year, in protest at the treatment of black Americans.
Speaking at a Republican rally on Friday, Trump described those who knelt as “sons of bitches”, adding they should be sacked by team owners.
More than 20 players and staff from the Baltimore Ravens and the Jacksonville Jaguars knelt or linked arms before their match at Wembley on Sunday.
There was a similar response at all of the weekend’s NFL matches, with three teams remaining in the locker rooms or tunnel for the duration of the anthem.
NFL commissioner Roger Goodell praised the players, saying Trump’s comments “demonstrate an unfortunate lack of respect for the NFL, our great game and a failure to understand the overwhelming force for good our clubs and players represent in our communities”.
Trump said on Monday his previous comments had “nothing to do with race” but were about “respect for our country, flag and national anthem”.
