Rams center Coleman Shelton was injured on the team’s first possession.
On a third-and-19 from the San Francisco 28, Darrell Henderson ran off left tackle for 7 yards. Shelton stayed down and then needed help off the field.
He left for the training room but ran back to the huddle before the next possession.
But, on the first play of the Rams’ second possession, 49ers linebacker Dre Greenlaw accidentally rolled onto the back of Shelton’s ankle while tackling Cam Akers. Shelton returned to the training room.
The Rams now have ruled out Shelton with an ankle injury.
Shelton slid to center after the starter, Brian Allen, underwent a procedure on his knee after injuring it in the season opener. Third-stringer Jeremiah Kolone now is playing center.
He spent time snapping to Matthew Stafford on the sideline after Shelton initially went out.