SANTA CLARA, Calif. -- While the San Francisco 49ers will be without left tackle Trent Williams for a fourth straight game Thursday night, there's at least a chance for three other key players to be available.
The Niners officially ruled out Williams (left ankle), safety Malik Mustapha (chest, shoulder) and guard Ben Bartch (high ankle sprain) Wednesday afternoon, but defensive end Nick Bosa (left hip, oblique), running back Isaac Guerendo (foot) and linebacker Dre Greenlaw (Achilles) are listed as questionable.
Bosa has missed the past three games after aggravating his left side in a Nov. 17 loss to the Seattle Seahawks. While the 49ers didn't do anything beyond a walk-through in practice the past three days because of the short turnaround, Bosa was listed as a limited participant in Wednesday's session. It's the first time he has participated at all since Nov. 15.
Greenlaw, meanwhile, has yet to play a snap this season after tearing his left Achilles tendon in Super Bowl LVIII. San Francisco opened Greenlaw's 21-day practice window on Nov. 27 with an eye toward his return coming this week.
On Monday, Niners coach Kyle Shanahan said Greenlaw had "a chance" to be activated to play against the Los Angeles Rams, depending on how the week went.
"We'll see," Shanahan said. "I haven't talked to him yet, so we'll see when he gets in here tomorrow, how he's feeling, how practice goes Tuesday and Wednesday and make our decision then."
Based on the injury report, Greenlaw had little issue this week. He was a limited participant in each practice he has participated in over the past couple of weeks but was listed as full for the first time for Wednesday's walk-through.
If the 49ers do activate Greenlaw, they would need to make a corresponding move before Thursday night's game. The obvious option would be to place Bartch on injured reserve to create a spot for Greenlaw on the 53-man roster.
As for Guerendo, he did not do anything Monday or Tuesday but was upgraded to limited in Wednesday's walk-through. After injuring the foot against the Chicago Bears last week, Guerendo insisted he would be OK to play against the Rams.
"Everything is fine," Guerendo said Sunday. "They're just being cautious. We have a quick turnaround this week, so we're just making sure that we're good to go."
The 49ers are already without Christian McCaffrey (right PCL), Elijah Mitchell (hamstring) and Jordan Mason (high ankle sprain) at running back. If Guerendo can't play or is limited, Patrick Taylor Jr. would be next in line for work out of the backfield with practice squad back Ke'Shawn Vaughn and recently added Israel Abanikanda also available as options.
Mustapha's absence comes as a bit of a surprise after he was listed as limited Monday and Tuesday. But he didn't participate Wednesday and was ruled out. Ji'Ayir Brown and Tashaun Gipson Sr. are San Francisco's top options to start in place of Mustapha alongside Talanoa Hufanga.