The San Francisco 49ers got back to winning ways without Nick Bosa and Trent Williams in Week 14, but their odds of keeping their season alive against the Los Angeles Rams would be much improved if they have those two All-Pros available.

But it remains unclear whether either will have a chance to make their return in a must-win Thursday Night Football matchup. 

Speaking to reporters in a conference call on Monday, head coach Kyle Shanahan said the pair are essentially in the same situation in which they have existed since the 49ers' Week 11 loss to the Seattle Seahawks, with both being evaluated day by day. 

Bosa (hip/oblique) was initially listed as doubtful for Sunday's win over the Chicago Bears before being downgraded to out on the eve of that matchup. Like Bosa, Williams (ankle) has not practiced at all over the course of the last three weeks.

The 49ers sacked Caleb Williams seven times without star pass rusher Bosa in the defeat of Chicago, while Jaylon Moore has filled in admirably for future Hall of Famer Williams at left tackle.

But both sides of the trenches would obviously be much better equipped to deal with the significant challenge posed by the Rams if even one of Bosa or Williams is able to return. 

There will be some more changes on the offensive side of the trenches for the Niners, with left guard Aaron Banks clearing the concussion protocol. He will slide back into his starting role, with Spencer Burford set to be his backup after Ben Bartch suffered a high ankle sprain early against the Bears. Bartch will be placed on injured reserve.

It is unclear which running back will be rushing behind the 49er O-Line. Shanahan confirmed rookie Isaac Guerendo did indeed suffer a foot sprain in going for 128 scrimmage yards and two touchdowns in his first start, but did not rule out the fourth-round pick.

"We'll evaluate him over the next few days, see if he's got a shot [for Thursday]," Shanahan said.

"We'll see if he can go on Thursday, but definitely can't go today," Shanahan added. "It's a quick turnaround, so we've got to evaluate him hard each day. I'll be surprised if he does much tomorrow. But hopefully, Thursday will be enough time for him."

If Guerendo is not able to go, then Patrick Taylor Jr, Ke'Shawn Vaughn and Israel Abanikanda will share the workload in the backfield. 

The 49ers have yet to make a decision on whether linebacker Dre Greenlaw will make his long-awaited return from his Super Bowl Achilles injury on Thursday.

"There's a chance [he'll play]," Shanahan added. "We'll see. 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 we'll make our decision then."

Meanwhile, at the same position, Dee Winters is day-to-day with an ankle injury. and Demetrius Flannigan-Fowles remains day-to-day after missing the win over the Bears with a knee issue. Rookie safety Malik Mustapha (chest) is also day-to-day.

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