MIAMI (AP) — A woman performing the national anthem before an NBA preseason game in Miami on Friday night did so while kneeling at midcourt, and opening her jacket to show a shirt with the phrase "Black Lives Matter."

The singer was identified by the Heat as Denasia Lawrence. It was unclear if she remained in the arena after the performance, and messages left for her were not immediately returned.

Heat players and coaches stood side-by-side for the anthem, all with their arms linked as has been their custom during the preseason. Many had their heads down as Lawrence sang, and the team released a statement saying it had no advance knowledge that she planned to kneel.

"We were unaware of it ahead of time."

— Miami HEAT (@MiamiHEAT) October 22, 2016