NWSL's Portland Thorns and North Carolina Courage were the first to kneel, right before playing in the Challenge Cup tournament opener at Zions Bank Stadium in Herriman, Utah. Both teams kneeled during the National Anthem while wearing shirts that said Black Lives Matter.
Players on the Chicago Red Stars, Washington Spirit, OL Reign and Sky Blue FC also knelt at each of their opening games.
On Tuesday, coaches, staff members and even match officials knelt during the National Anthem before a match between the Houston Dash and Utah Royals FC.
On Monday, the NWSL had announced that players now have the option of either being on the field or remaining in the locker room during the National Anthem. This decision was made following conversations with players from around the league, as well as club officials and other stakeholders, a news release said.
"We're going to continue to play the National Anthem, but with even more flexibility, and support each player's right to express their individual views, or not," NWSL commissioner Lisa Baird said.
"The NWSL stands behind every player, official and staff member. Kneel on the field. Stand with your hand over your heart. Honor your feelings in the privacy of the locker room or at midfield. The NWSL is a league that was built on diversity and courage and those principles will continue to drive us forward."
North Carolina Courage and the Portland Thorns NWSL players released a joint statement on Saturday explaining their decision to kneel during the National Anthem:
"We took a knee today to protest racial injustice, police brutality, and systemic racism against Black people and people of color in America. 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."
The protests overshadowed the significance of having the first professional team sport return amid the pandemic.
Former San Francisco 49ers quarterback Colin Kaepernick started kneeling during the National Anthem in 2016 to protest police brutality and oppression. Today, protests against racism and police brutality continue across the US following the deaths of George Floyd, Breonna Taylor and Rayshard Brooks.
While players across different sports have knelt in protest in some form or other, having nearly every player on every NWSL team kneeling together was a powerful display.
Major League Soccer, which is the premiere men's league in the US, is opting to not play the National Anthem citing a lack of fans in the stands.
The NWSL Challenge Cup is a 30-day tournament taking the place of the league's regularly scheduled 2020 season, which typically runs from April to October with all nine teams playing 24 games.