The Rams are feeling heat from the Seahawks and 49ers having lost two in a row. So this becomes a crucial game. Sean McVay is the best coach in the NFC. Jared Goff has a history of playing much better at home. 
The 49ers are not used to taking on opponents who are extremely motivated to play them - until now. San Francisco is much improved as its 4-0 record attests. But do note those victories have come against the Buccaneers, Bengals, Steelers and Browns. The combined record of those teams is 5-15. 
LA is on extra rest having played last Thursday. The Rams are 7-1 ATS when having a rest advantage under McVay. The 49ers, on the other hand, are on a short week coming off a great Monday night home win against the Browns. Lost in the glare of the 49ers' dismantling of the Browns, though, was two key injuries - fullback Kyle Juszcyk and offensive right tackle Mike McGlinchey. Both are out long-term. Juszcyk may be the best fullback in the league. Compounding McGlinchey's injury is San Francisco already is minus star offensive left tackle Joe Staley.
Aaron Donald should be in for a monster game. The Rams' defense isn't as down as some may perceive. LA's offense has been turning the ball over, which has put its defense in difficult field position. 
Jimmy Garoppolo doesn't have that much starting QB experience. He's going to face a heavy pass rush without his starting tackles. I don't see him keeping up with a high caliber Rams offense that should be well-designed with nine days to prepare under QB guru McVay. Todd Gurley may not play, but the Rams have two other good running backs. 
One of the keys to McVay's success has been a 10-3 division record. The 49ers are 2-10 against NFC West foes under Kyle Shanahan.