ENGLEWOOD, Colo. — Offensive linemen Ron Leary (concussion) and Ja'Wuan James (knee) did not practice on Wednesday and may not be able to play on Sunday against the Lions.

"Ron is still having difficulties with his concussion, so I don't think it looks good right now," Head Coach Vic Fangio said. "Ja'Wuan probably won't play either."

Leary suffered a concussion against the Chargers and has not practiced since. James, who has appeared in just three games this season, has not played since the first half of the Broncos' Week 14 game in Houston.

"I don't think he feels that it's 100 percent right now, so he's a little leery right now," said Fangio of James on Monday.

Austin Schlottmann has started the last two games at right guard for the Broncos, and Elijah Wilkinson has started nearly every game at right tackle in James' place.

Defensive ends DeMarcus Walker (ankle) and Adam Gotsis (knee) and guard Dalton Risner (illness) also missed practice.

Tight end Noah Fant (shoulder), defensive end Dre'Mont Jones (ankle) and linebacker Joe Jones (back) were listed as limited.

The Broncos will also be without safety Kareem Jackson, who was designated as Reserve/Suspended on Tuesday. Jackson will miss Denver's final two games of the season. Against the Lions, Trey Marshall will start for him at safety and Will Parks will assume the nickel cornerback role.

"We haven't seen Trey play a lot of defense since preseason, but he gets reps in practice and we're confident he can go out there and do his job," Fangio said.