Ben Simmons sat out the Philadelphia 76ers' home opener on Friday night for personal reasons and the franchise does not know when the three-time All-Star guard will return.

Simmons was suspended for the first game of the season for conduct detrimental to the team after coach Doc Rivers threw him out of practice for refusing to participate in a drill.

He returned Friday and addressed the team before the opener against Brooklyn.

Rivers said it was a "productive day" and hoped the meeting was a start toward bringing Simmons back into the fold.

"It still doesn't mean things will work out perfect, or it could," Rivers said. "I've always believed that. I've never wavered from that."

Simmons averaged 15.9 points, 8.1 rebounds and 7.7 assists over four seasons with Philadelphia, which drafted him No.1 in 2016 out of LSU, where he played only one season.

His defining moment as a Sixer came when he passed up a wide-open dunk against Atlanta in the second round of last year's playoffs that would have tied the game late in Game 7. Simmons took the blame for Philly's early post-season exit.

Rivers said he didn't want to predict when Simmons might rejoin the Sixers - if the guard returns at all.

"We're going to make sure Ben's with the right people and see where that goes," Rivers said. "He is part of the team. We have certain rules, obviously. The other day, that didn't happen. But today was a good day."

Tobias Harris said after Brooklyn beat the Sixers 114-109 teammates, fans and the entire organisation needed to respect Simmons' privacy and give him the space he needs until he decides to play again in the NBA.

"I think at this time, he needs more support than neglect," Harris said.

"I think we've just got to be there for him as a team. I've relayed that to the group.

"And I hope that message is loud and clear to our fans and everybody around the organisation, and also you guys as well in the media."

The Sixers play road games Sunday and Tuesday. They return home Thursday against Detroit.