CHICAGO -- Bulls coach Billy Donovan wasn't sure when or even if Lonzo Ball will play again for Chicago, with the point guard set to have yet another surgery on his troublesome left knee.

Donovan said Ball will likely undergo a cartilage transplant early next week, though he wasn't sure which day, and is in for "a long rehab."

ESPN's Adrian Wojnarowski reported Thursday that concerns persist about Ball's eventual ability to resume his career and that the latest procedure could cost him most -- if not all -- of the 2023-24 season.

"For me to say, 'I have no hope that he's ever going to play here again' or 'yeah, he's definitely going to be back,' I just don't know," Donovan said Friday.

One thing that gives Donovan optimism is Ball's work ethic and attitude.

"Even though he comes in, he's around the team for a period of time, there is a lot of time that he's away from everybody," Donovan said. "Just having to come to grips of not playing is really, really hard, I think, probably for him to absorb. But he handles himself incredibly well. He's so consistent all the time with his spirit and disposition and what he's tried to do every step of the way to get back."

The surgery will be the third on the knee in 14 months for Ball, who also had it scoped in 2018 when he was with the Los Angeles Lakers. The Bulls ruled him out for the season in February.

"The fact that the game's been taken away from him and he can't play, you just feel terrible for him because he loves the game, he loves playing," Donovan said. "You see everything he has done since this happened to try to get himself back on the court, and you always want to see a guy get rewarded by putting in the work that he's put in to get back."

Ball hasn't played since a loss to Golden State on Jan. 14, 2022. He had surgery for a torn meniscus a few weeks later that was expected to keep him out six to eight weeks, but he experienced setbacks when he tried to ramp up basketball activities.

The Bulls had him rest for 10 days at one point, hoping it would resolve the issue and allow him to return. But he felt pain again when he started preparing to play.

Ball was still unable to run at full speed or even walk up stairs without experiencing discomfort when he had another operation in late September. He said at the time he expected to play this season.

Ball has been able to do some on-court work. He posted a video on Instagram in January of him dunking. But it became more and more clear that a return to play probably wouldn't happen.

Ball averaged 13 points and 5.1 assists while shooting 42.3% on 3-pointers over 35 games last season, his first in Chicago. He helped set up stars Zach LaVine and DeMar DeRozan and gave the Bulls an elite perimeter defender.

Information from The Associated Press was used in this report.