All 22 starters from the North Carolina Courage and Portland Thorns, along with reserves from both teams, knelt during the national anthem before the opening game of the NWSL Challenge Cup on Saturday.
Starters and reserves also knelt briefly for a second time immediately before kickoff. All players wore Black Lives Matter shirts over their jerseys during the anthem and Black Lives Matter armbands during the game.
The game in Herriman, Utah, marked the return of professional team sports leagues in the United States. The leagues had been on hiatus since March because of the coronavirus pandemic.
Players from the two teams issued a joint statement shortly before kickoff.
"We took a knee today to protest racial injustice, police brutality, and systemic racism against Black people and people of color in America," the statement read. "We love our country and we have taken this opportunity to hold it to a higher standard. It is our duty to demand that the liberties and freedoms this nation was founded upon are extended to everyone."
During Saturday's late match between the Chicago Red Stars and the Washington Spirit, a few players remained standing. There was a touching moment when Chicago's Julie Ertz consoled teammate Casey Short, who was overcome by emotion.
Spirit Coach Richie Burke joined his players in kneeling before the late game.
"I'm grateful for everything this country has given me, but I feel the need to support the Black Lives Matter movement because I know this privilege isn't the same for everyone,'' Burke said. "This is just the start. There is much more work to be done."
Many European professional soccer leagues adopted the kneeling gesture in recent weeks in response to the protests following the death of George Floyd, a Black man who died May 25 after Derek Chauvin, a white police officer, knelt on his neck for more than seven minutes in Minneapolis.
Fans will not be in attendance for any of the NWSL games during the monthlong tournament in Utah, but the anthem was played live on the field and broadcast live on CBS.
"Today, hopefully, it was a powerful statement," Courage midfielder Sam Mewis said after her side's 2-1 victory. "It was an emotional time, and I hope that both teams' message comes through clearly."
You love to see it. You love to see these women using their voice, demanding better for America, and for black people and people of color. @TheNCCourage and @ThornsFC kneeling in solidarity with @Kaepernick7 and @Blklivesmatter ✊🏻✊🏼✊🏽✊🏾✊🏿 pic.twitter.com/8Urlj5FMPn— Megan Rapinoe (@mPinoe) June 27, 2020
Thorns defender Becky Sauerbrunn said: "The [players' association] has been about collaborating with teams on what we can do to maintain and sustain the conversation around racial injustice in this country.
"We made a strong statement, and we wanted to kind of maintain that momentum that has been happening and to show official commitment to the cause."
In addition to kneeling during the anthem for two games with the United States Women's National Team in 2016, Megan Rapinoe knelt before an NWSL game while playing with the Seattle Reign.
Rapinoe, who now plays for OL Reign, as the team was rebranded this offseason, tweeted her support for the players after seeing the display.
"You love to see these women using their voice, demanding better for America, and for black people and people of color," the post said, in part.
Information from The Associated Press was used in this report.