The 49ers on Tuesday re-signed defensive back Tyvis Powell to the 53-man roster and placed cornerback Ahkello Witherspoon on injured reserve.
Witherspoon sustained a partially torn posterior cruciate ligament in his right knee Sunday in the first quarter of the 49ers’ 26-23 victory over the Seattle Seahawks.
Witherspoon, a third-round draft pick in 2017, appeared in 14 games this season with 12 starts. He recorded 37 tackles and broke up for passes. After a slow start to the season, Witherspoon had played much better in coverage in recent weeks.
Rookie cornerback Tarvarius Moore replaced Witherspoon at right cornerback and is in line to start the final two games of the season.