How are Nick Bosa and Trent Williams trending for 49ers' must-win Rams clash? - Kyle Shanahan has the updates

The San Francisco 49ers' Week 15 game with the Los Angeles Rams is a must-win, one for which they need all hands on deck.

But it's looking increasingly likely they will once again be without two of their most important players. 

Speaking ahead of Tuesday's practice for the Thursday Night Football matchup with the Rams, head coach Kyle Shanahan revealed that defensive end Nick Bosa and left tackle Trent Williams would once again sit out.

The All-Pro pair have missed the last three games due to their respective injuries. 

On top of that, running back Isaac Guerendo, who suffered a foot sprain late in an impressive first start in the 49ers' blowout win over the Chicago Bears on Sunday, remains a major doubt for the Rams game after Shanahan confirmed he would also miss practice. 

Jaylon Moore will continue at left tackle if Williams is ruled out for a fourth straight game. Sam Okuayinonu has started at defensive end across from Leonard Floyd in Bosa's absence, though Yetur Gross-Matos had three sacks in the win over the Bears.

Linebacker Dre Greenlaw's long-awaited return from the Achilles injury he suffered in the Super Bowl has yet to be confirmed. Shanahan said that he would be limited in practice along with Gross-Matos (knee), rookie safety Malik Mustapha (chest) and linebacker Demetrius Flannigan-Fowles (knee).

Guard Ben Bartch was also listed by Shanahan as a DNP. He is headed for injured reserve after suffering a high ankle sprain against the Bears.