LAKE FOREST, Ill. -- Middle linebacker D.J. Williams returned to practice on Tuesday for the first time since suffering a July 31 right calf injury, but the club’s plan for him moving forward is murky with the starters not expected to play Thursday in the preseason finale and the regular-season opener nearly two weeks away.

Williams didn’t participate fully in practice.

“But he’s getting more work,” Bears coach Marc Trestman said.

Williams took part Monday in pre-practice stretching, and has also spent some time running. But Trestman said Monday that Williams’ conditioning could be an issue for the opener. So there’s a chance the team could opt to hold out Williams in favor of rookie second-round pick Jon Bostic, who has filled in as the starting middle linebacker.

“I couldn’t answer that question,” Trestman said when asked whether Williams would be ready for the opener. “Each and every day he gets a little better, and we’ll know a lot more at the beginning of next week. He’s got four or five days before our first day of practice on Monday. So we’ll see how it is at that point in time. I can’t answer the question other than there’s improvement there. Talking to him, he’s certainly positive that he can be ready. Players are always that way. They are, and they should be. We’ll see. I’m encouraged, but we don’t know at this time.”

The Bears signed Williams to a one-year contract in March worth $900,000 as the replacement at middle linebacker for Brian Urlacher, and drafted Bostic as the future at the position.

But Williams’ calf injury pushed Bostic into the starting spot, and the rookie has turned heads with big hits and game-changing plays such as his interception return for a touchdown in the exhibition opener at Carolina.

Still, Trestman wasn’t ready on Monday to declare Bostic the starter.

“Well, I am not going to use that term ‘starting middle linebacker,’” Trestman said. “(Bostic) has started in the last couple games, and I think he has continued to grow and get better, and shown he can be a very good player in this league. He is fitting in and if he happens to be the guy who is that guy on Game 1 or Game 2 or whatever it is, I think he can grow into the position and be a more than sufficient middle linebacker in this league.”

With Williams still technically a starter, it’s unlikely the Bears would place him in harm’s way by giving him snaps Thursday against the Cleveland Browns. Given that Williams has missed virtually all of training camp and the preseason, he won’t have any way to compete with Bostic for the starting job.

Perhaps Williams’ long track record in the NFL is sufficient enough for the staff. Before joining the Bears, Williams played in 127 games for the Denver Broncos with 115 starts and has posted 886 tackles (673 solo) to go with 20.5 sacks, two interceptions, 14 forced fumbles and seven recoveries. Throughout his career, Williams has posted five 100-tackle seasons.

“There’s always competition. It’s compete to play, compete to stay,” Bears defensive coordinator Mel Tucker said. “So there’s nothing ever set in stone. You’re only as good as your next play. That’s what we preach to the guys. So every time out is important. Every practice is important, every meeting, every rep that we take in a game. It all means something.”

In other injury news, the Bears practiced Tuesday without offensive tackle Jonathan Scott (knee), defensive tackle Corvey Irvin (ankle), cornerback Zack Bowman (hamstring), and running back Harvey Unga (undisclosed).

The team also held out defensive tackle Henry Melton and receiver Earl Bennett, who continue to go through the concussion protocol. Melton and Bennett took part in pre-practice stretches with teammates, and they’re also working on physical conditioning.

Trestman believed that Tuesday marked the first time Bennett had run since suffering the concussion.

“Earl and Henry both got running in today,” he said.