Jonathan Isaac stands for the national anthem before the Orlando Magic's victory over the Brooklyn Nets.
Later on Friday San Antonio Spurs head coach Gregg Popovich and assistant coach Becky Hammon also stood.
On Thursday all players from the four teams in action all knelt during the pre-match anthem.
Isaac, who chose not to wear a Black Lives Matter t-shirt, said: "Absolutely I believe Black Lives Matter."
He added: "A lot went into my decision ... kneeling or wearing a Black Lives Matter T-shirt doesn't go hand in hand in supporting Black lives."
Isaac had told his team-mates earlier in the week of his decision. They all chose to kneel before their 128-118 win over the Brooklyn Nets.
"That's a personal decision," said Magic coach Steve Clifford. "We're all supporting each other in this. And if guys are not comfortable kneeling and they want to stand, nobody has a problem with that. I support him. His team-mates support him. The organisation supports him. That's part of living in our country." Read more >>