The Chicago Bulls have a defensive problem.

That was clear before the team ever stepped on the court. The Bulls are projected to field a starting rotation of offensive-minded guards with a reputation for letting things slip on the other end of the floor. Two years after fielding one of the best defensive units in the league, the Bulls are likely on track to start one of the most porous defenses in the NBA.

The solution for this problem might not exist. But if it does, it rests on the shoulders of a player still trying to spark his breakout season in Chicago: fifth-year forward Patrick Williams.

At 6-foot-7, Williams is the most versatile matchup on the court for the Bulls, locking up opponents on the perimeter and providing crucial rim protection in the paint. But the forward doesn’t want to buy too much into the pressure of anchoring the starting group on defense.

“It doesn’t really change anything for me,” Williams, 23, said. “I try to guard one-on-one and I try to make plays. That’s pretty much what it’s been about. Certain guys can make certain plays that other guys can’t. That’s just the NBA.”

Coach Billy Donovan hasn’t been hesitant to share his worries for the defense.

The trade of Alex Caruso — combined with the dip in rim protection following Andre Drummond’s free-agency exit — leaves the Bulls with plenty of gaps to fill. And after three years of leaning heavily on some of the best clean-up defenders in the league, the defense will have to support itself.

“We don’t have Alex out there,” Donovan said. “Even with Lonzo — in pick and roll coverage, you know, bigs would call out the coverage and those guys were like, ‘You don’t need to call anything. I got it.’ They were that good defensively. It’s not to say that we can’t get it done. We’re just going to have to do it collectively.”

A single preseason game isn’t enough to fully diagnose the strengths or weaknesses of a roster. As guard Ayo Dosunmu put it Thursday: “You don’t want to be perfect in preseason. That would be alarming.”

But Tuesday’s win against the Cleveland Cavaliers highlighted the cracks in the foundation of the Bulls defense, which coughed up 67 points in the first half despite the fact the Cavs shot below 27% from behind the arc.

For Donovan, the most pressing concern was the disjointed nature of the team’s defensive approach. The game plan explicitly told the guards not to switch in screen actions involving players such as Evan Mobley, whose length guaranteed a mismatch in the post. Yet throughout the first half, Donovan watched as guards constantly switched off screens, giving Mobley free space to work down low.

“We had so many blown situations in the half court with two players coming together in screening actions,” Donovan said. “We didn’t communicate well enough.”

For the Bulls starting lineup, the concept of collective defense starts and ends with Williams.

Williams is quick to downplay his defensive importance. He feels the main Bulls rotation is better defensively than meets the eye — Coby White has made significant growth as a defender, Josh Giddey is deceptively long for a guard and Ayo Dosunmu will bolster the group off the bench.

But Williams won’t be able to brush off the weight of his role once the season tips off. Donovan projects that Williams will spend some time at the 5 throughout the season to maximize the advantage in speed for the undersized roster. Williams will be asked to defend guards, wings and centers, a workload he has slowly built into over the years with the Bulls.

While adapting to these matchups will be a challenge, Williams is eager to embrace the project as a cornerstone of his growth.

“I’m trying to have as many tools as I can,” Williams said. “For me — individually, selfishly — that’s kind of what I’m trying to get to. That’s my mindset each day that I step on the floor — what can I add to my toolbox, what can I add to my tool set so that three, four years down the line I know how to guard the 4, I know how to guard a wing. That just kind of helps us later on in playoff time.”

Lonzo Ball unlikely to make return Saturday

Donovan said the Bulls do not expect guard Lonzo Ball to play in Saturday’s home preseason game against the Memphis Grizzlies. Ball is expected to return to the Bulls lineup by the end of the preseason, but Donovan said Ball still has not cleared the threshold for the medical team to OK him for a game.

“He’s practicing with contact today,” Donovan said. “He went out there, still building him up there. But I would not anticipate him playing.”

Donovan said the guard has not experienced any setbacks in training camp, during which he has been heavily limited in contact drills.

Ball is still expected to be available for the Oct. 23 season opener, which would be his first NBA game since initially injuring his left knee in January 2022.

Neither Patrick Williams (foot) nor Josh Giddey (ankle) experienced setbacks after playing Tuesday. Jalen Smith rolled his ankle in the game but was cleared for full action in Thursday’s practice after a rest day Wednesday.