CHICAGO -- The Chicago Bulls expressed optimism on Thursday following guard Lonzo Ball's latest surgery to address the lingering discomfort in his left knee, but his timeline to return to the court remains uncertain.

Bulls coach Billy Donovan met with director of athletic performance Chip Schaefer, who was in Los Angeles earlier in the week for Ball's surgery, before practice on Thursday and received reports that Ball's second knee operation since January "went well" and that Ball was in good spirits.

However, Donovan acknowledged that until Ball resumes his rehab process, it's difficult to determine when the Bulls might get their point guard back.

"You always try to stay optimistic that this will get resolved and he'll be fine," Donovan said after practice Thursday. "But until he gets back and gets into the situations that were causing him pain, to see how he responds in being back in those situations, we'll find out more. I don't know how long it will take before he can actually start the rehab process."

Before the surgery, the Bulls announced they intended to reevaluate Ball in four to six weeks, which will keep him sidelined until that checkpoint around the start of November. He is expected to return to Chicago to continue his rehab around the team.

Ball, who turns 25 next month, has not played in a game since Jan. 14, when a torn meniscus was supposed to sideline him for a few months with the hope of returning for the playoffs. Instead, the injury has made for a perplexing saga that has been ongoing for most of the calendar year, leaving Ball and the team searching for answers. After spending all summer trying to rehab the knee and avoid surgery, Ball said this week's operation was intended to both identify the issue in his left knee and correct it.

"I'm at a point where I just want to get it over with and get healthy and get back to playing," Ball said earlier this week. "I missed the playoffs last year. I haven't played basketball pretty much all year. So for me, I just want to get out there with my teammates and do what I love to do."

This is his second arthroscopic surgery on his knee since the end of January, and third in his career. Ball said earlier this week prior to the surgery that he has not been able to run or jump on a basketball court and his knee is bothering him in everyday tasks, such as walking up stairs.

"You've also got a player that's been out for nine months," Donovan said. "It's not like in three weeks, the surgery is a success, you can just throw him back out there and play.

"We haven't even gotten to the point if this all goes well with the rhythm, timing, the flow, catching up. He's had no competitive play since [January]. So that's a whole other scenario of when he could actually get back."