Rivers is believed to have a PCL sprain that could sideline him for multiple weeks, Ian Rapoport of NFL Network reports.
Rivers will undergo an MRI to confirm the diagnosis, but the initial prognosis does not bode well for his chances at suiting up in Week 7 versus Pittsburgh. With Kyren Williams (ankle) dealing with an injury of his own, the Rams could be severely short-handed in their backfield for that contest.