The move came three days after Lassiter tore his right MCL.
Lassiter trails only linebacker Donnie Edwards with 50 tackles in 10 games. He also scored on a 38-yard interception return last month against Cleveland.
Rookie Terrence Kiel will move into the starting lineup after seeing time in passing situations in each of the first 10 games. He shares the team lead with two interceptions and has 28 tackles while also seeing action on special teams.
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