Rams rookie linebacker Josh Forrest will miss four to six weeks after suffering a knee injury during Sunday's 14-10 loss to the Miami Dolphins, according to Los Angeles coach Jeff Fisher.
Fisher said Monday the Rams "most likely" will place Forrest on the injured reserve list and promote linebacker Nic Grigsby from the practice squad to help on special teams. The coach did not specify the nature of Forrest's injury.
Forrest, 24, injured the knee on a second-quarter collision with teammate E.J. Gaines. Forrest was chasing Dolphins quarterback Ryan Tannehill near the sideline when he tripped over Gaines as Gaines was pushed down.
A sixth-round draft pick out of Kentucky, Forrest has recorded three solo tackles, a pass deflection and a fumble recovery while serving as the Rams' third linebacker, after Alec Ogletree and Mark Barron. His playing time has been inconsistent this season, because the Rams primarily use a nickel set that requires only two linebackers.
From the Rams' fifth to ninth games this season, Forrest played 44 percent, 26 percent, 2 percent, 19 percent and 7 percent of the defensive snaps, respectively.