Update: Jake Long has re-entered the game in the third quarter.
With 17 seconds left in the first half, Long was blocking a defensive tackle when Niners linebacker Ahmad Brooke was pushed into Long's leg, causing it to collapse under the him. Long remained down on the field for some time, before walking off under his own power. His return is listed as probable, according to Brian Feldman.
Long was signed in free agency this year to help protect quarterback Sam Bradford. The veteran struggled more than expected, causing the Rams to rotate him to offensive guard while Max Starks played left tackle. The injury occurred while Long was playing the left guard position.
Injury concern was the primary reason the Miami Dolphins elected to part ways with the four-time Pro Bowler and former No.1 overall pick. Long missed four games in 2012, and two in 2011 as well as addition sporadic snaps off.