The Dallas Cowboys knelt as a team near the 50-yard line prior to the national anthem before Monday night's 28-17 win over the Arizona Cardinals at University of Phoenix Stadium.
Then they locked arms and stood while Jordin Sparks sang the national anthem.
Team owner and general manager Jerry Jones and his family joined the team on the field for the display of unity. The Cowboys' official Twitter account posted a message and photo soon after the anthem, stating "#FootballIsFamily."
But there were audible boos as well, even catching the attention of President Donald Trump, who tweeted Tuesday morning that it "was [the] loudest I have ever heard. Great anger."
Trump has claimed that kneeling during the anthem is disrespectful to American servicemen and -women and the national anthem. The protest began as a way to highlight police mistreatment of minorities but took on a new meaning last week when Trump referred to any player who took part in it as a "son of a bitch" who should be fired. That comment, made at a rally in Alabama, sparked far more protests and widespread shows of unity.
The Cardinals took part in a show of unity on Monday as well, gathering on the goal line as a team, with some players locking arms, during the anthem. Cardinals owner Michael Bidwell and his family and general manager Steve Keim joined them.
Trump did note that the Cowboys avoided kneeling during the anthem: "But while Dallas dropped to its knees as a team, they all stood up for our National Anthem. Big progress being made-we all love our country!"
After the game, Jones told the media that the Cowboys' demonstration was about a "need for unity and equality," and he said he was very proud that the Cowboys stood for the flag, adding that he did not talk any Cowboys players out of kneeling during the anthem if they chose to do so.
"I wanted our actions to be louder than words," Jones said. "We did it."
Cowboys head coach Jason Garrett said the discussions among the team about how they would demonstrate went right up until a few minutes before kickoff.
"The objectives, as much as anything else, was to somehow, some way demonstrate unity and demonstrate equality," he said. "And do so without any way involving the American flag and the national anthem."
Quarterback Dak Prescott said the decisions about how the Cowboys would demonstrate, "weren't that tough. Nobody is here to judge anybody else."
The protests began last season with then-San Francisco 49ers quarterback Colin Kaepernick, who has repeatedly explained that he took a knee as a way to protest police brutality and racism facing minorities in America, especially people of color.
On Friday, Trump said players who protest during the national anthem should be fired, but the comments sparked even more protests by NFL players during Sunday's games.
Trump then carried his feud with the NFL over players who kneel in protest into the new week with a fresh volley of tweets.
"Tremendous backlash against the NFL and its players for disrespect of our Country. #StandForOurAnthem" he wrote Monday evening.
Trump's views sparked backlash and were considered racist by some.
"The issue of kneeling has nothing to do with race. It is about respect for our Country, Flag and National Anthem. NFL must respect this!" he said in one of his Monday tweets.
NFL spokesman Joe Lockhart defended players' rights to peacefully protest what they view as racial inequality and police mistreatment of black males.
At Woody's Tavern on Bryant Irvin Road in south Fort Worth, Cowboys fans watched the national anthem with great anticipation. Robert Maddox and friend Kacey Clauser are both die-hard Cowboy fans but had different opinions on the pregame controversy.
"I hope they stand," said Clauser, an off-duty bartender.
Maddox said the players should do whatever they want.
"I support them more than I support Donald Trump right now for his actions," he said. "What has he done good for us lately? Honestly."
They watched as the Cowboys knelt in solidarity before the national anthem and then stood for the performance.
"They got their message across, but still did the right thing," Clauser said.
"I respect everything the Cowboys do," he said. "They're respectful. They're the nation's team."
NBC 5's Scott Gordon contributed to this report.