World Peace, 35, played four years with the Lakers, winning a title with the team for the 2009-10 season, leaving in 2013 under the team's amnesty waiver. He didn't play last season, after a short stint with the New York Knicks in 2013-14.
The Lakers now have a roster of 19 players, with 12 contracts fully guaranteed. The regular season maximum is 15.
The veteran has spent much of the summer scrimmaging with the team's second-year forward Julius Randle.
"It's great to have him go against Julius, to watch those two guys practice, it's almost comical," said Kupchak. "I'm not sure who gets the better of it. I would be surprised if either player admitted to anybody after practice that they hurt more than they did before practice.
"I could see Julius going home and getting in a tub, but I could see Metta getting in a tub too -- but you wouldn't know it because they wouldn't tell you. They're both mega-competitors. Clearly Metta is much closer to the end than the beginning."
Kupchak said that World Peace can still be competitive on the court in practice, but he questioned if he'll be able to contribute over the course of an 82-game schedule.
"I think he'd be great in the locker room with young players, but we have to be careful not to use a roster spot too early because we have a lot of young kids ... that we're going to bring to camp," Kupchak said. "We don't want to put ourselves in a bind by getting 15 roster spots taken and not giving the young kids, who could be very talented, a chance to make the team. That's something that we're going to have to weigh."
In addition to World Peace, the Lakers are auditioning Tarik Black, Jabari Brown, Robert Upshaw, Jonathan Holmes, Michael Frazier and Marcelo Huertas. Holmes has $100,000 of his contract guaranteed, while Frazier is promised $50,000 and Upshaw $35,000.
Kupchak didn't rule out that a player with a fully guaranteed deal could be cut.
"We'll keep the best players," he said. "If there's a player that clearly outplays a player that's on a guarantee, then we can look to trade a player, and if we couldn't do that ... I think ownership would give us the flexibility to waive a [guaranteed] player if we had to."
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