PHILADELPHIA -- Chicago Bulls guard Lonzo Ball underwent cartilage transplant surgery on his left knee earlier Monday, a procedure coach Billy Donovan said gives Ball the best chance to, at some point in the future, resume his NBA career.

"I know he's going to work really hard [on his rehab]," Donovan said before Monday night's game against the Philadelphia 76ers. "[The doctors] felt like the surgery went well.

"I do know that Lonzo, just based on the information he was able to gather from different sets of doctors, [was] making the decision that he felt like this was the best chance to be able to get him back on the court. We all understand that that is going to be an uphill battle for him, but I know he's going to do everything possible in his rehab to get himself back on the court."

That was a similar message to the one Ball himself put forth in a release the Bulls put out last week announcing he'd be having a third surgery on his left knee in a little more than a year.

"My main focus has been on returning to the court and getting to a place where I can rejoin my teammates," Ball said. "This has been a frustrating process, but I'm confident these next steps are the best path forward. The support of my family, friends, fans and medical staff throughout my recovery is what keeps me moving forward. I can't wait to get back to what I love doing most -- playing basketball."

Ball hasn't played in a game since Jan. 14, 2022. He initially had surgery a short time later to repair a torn meniscus in his left knee, and Chicago said then he'd be back in 6-to-8 weeks. After missing the rest of the season, and then continuing to have pain and discomfort in the knee over the summer, Ball had a second surgery in September.

"There was a point where we would warm up and stuff, and I would go through certain days and it would be fine," Ball told reporters at the time. "Then whenever I got to real basketball activities, I just couldn't do it. Unfortunately, this is what's at hand and has to be dealt with. We feel like surgery, again, is the best option.''

But after continuing to fail to progress enough to facilitate a return for this season, Ball was ruled out for the rest of the season last month.

ESPN's Adrian Wojnarowski reported last week that Ball's latest surgery could cost him most -- if not all -- of the 2023-24 season. All Donovan would say is that he was told Ball is out "indefinitely," and that he didn't have a timeline for his return beyond that.

"He's certainly got a long road to recovery, a long road to get himself at a place where he can get back on the court and playing again," Donovan said, "but I am hopeful with his work ethic and his commitment and drive and just how eager he is to play, that he's gonna exhaust every opportunity to do that."

Ball, 25, fit in seamlessly over the first half of last season alongside star wings Zach LaVine and DeMar DeRozan in Chicago, with his combination of size and length at the point, along with being one the league's best passers, a strong defender and an improved 3-point shooter.

Chicago went 27-13 last season before Ball left the lineup in mid-January, and then went 19-23 down the stretch ahead of losing in five games to the Milwaukee Bucks in the first round of the playoffs.

The Bulls entered Monday's game against the streaking 76ers, winners of a league-leading eight straight games. At 33-37, the Bulls are in the 10th spot in the Eastern Conference standings -- the final play-in spot, and 1.5 games ahead of the Washington Wizards and Indiana Pacers, who enter the night tied for 11th.