LAKE FOREST, Ill. -- The Chicago Bears returned to Halas Hall on Monday to resume practice with eight players sitting out the workout, including defensive tackle Henry Melton and receiver Earl Bennett, who are still advancing through steps of the concussion protocol.

"Henry and Earl are getting better," Bears coach Marc Trestman said. "It's still day-to-day there, and we're keeping our fingers crossed there that it will continue to improve as it has."

Melton suffered a concussion in the first quarter of the team's preseason opener at Carolina, while Bennett's head injury came due to a hit from teammate Chris Conte during an Aug. 3 night practice at Soldier Field. It's unlikely the Bears will make either player available for Friday's preseason matchup at Oakland. Neither attended the workout on Monday, as both are recovering at home.

In other injury news, starting middle linebacker D.J. Williams (calf), long snapper Patrick Mannelly (ribs) and offensive tackle Jonathan Scott (knee) were held out of Monday's workout, along with defensive end Cheta Ozougwu (hamstring), defensive tackle Corvey Irvin (ankle) and fullback Harvey Unga (ribs).

Trestman plans to meet with Williams "this week to just kind of spend some time with him to see where he is." With rookie second-round pick Jon Bostic putting together a couple of solid performances during preseason outings in Williams' place at middle linebacker, it's legitimate to ponder whether the rookie might unseat the veteran.

Bostic returned an interception for a touchdown against the Panthers in the preseason opener, and on Thursday against the Chargers he posted two tackles in addition to breaking up a pass.

While it's likely Williams will be healthy enough to play when the Bears play host to the Cincinnati Bengals on Sept. 8 for the regular-season opener, Trestman expressed concern about the veteran's conditioning level.

"We're getting close to the season. His conditioning now becomes an issue," Trestman said. "We think eventually he'll be back. We just don't know when. It's an improving situation. He's on schedule to come back over the time period that we expected him to. So we'll see what happens over the next few weeks. Hopefully, we'll get him out here to practice in the next 12 to 14 days or better."