League rules state NBA players, coaches and trainers must "stand and line up in a dignified posture along the sidelines or on the foul line" during the national anthem.
The rules don't say anything about the national anthem singer.
On Monday night, Leah Tysse took a knee as she performed the last lines of the anthem at the Sacramento Kings preseason opener at the Golden 1 Center.
The Berkeley resident's move did not go unnoticed online.
National anthem singer at the Kings game just took a knee!!— Kevin Fippin (@kfippin) October 11, 2016
The national anthem singer at the Sacramento Kings game took a knee for the final lines of the song.— Carmichael Dave (@CarmichaelDave) October 11, 2016
Tysse taking a knee comes after several weeks of professional athletes protesting the national anthem in various ways, including taking a knee.
The trend started with 49ers quarterback Colin Kaepernick during an August preseason game.