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SANTA CLARA -- The 49ers placed cornerback Chris Cook and center Daniel Kilgore on season-ending injured reserve on Saturday, and re-signed special-teams player Bubba Ventrone.
The 49ers currently have one roster spot available. It is unclear how the 49ers plan to fill that roster spot, but there remains the possibility that the NFL will reduce linebacker Aldon Smith's suspension by one or two games, league sources confirmed. Smith has already served seven of his original nine-game suspension.
The NFL has made no announcement on Smith's status.
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Kilgore underwent season-ending surgery Tuesday on a fractured left lower leg. Cook left the 49ers' game Sunday night with a hamstring injury. Cook signed a one-year, $730,000 contract with the 49ers in the offseason.
The 49ers now have four cornerbacks on their 53-man roster: Tramaine Brock, Chris Culliver, Perrish Cox and rookie Dontae Johnson. Rookie safety Jimmie Ward plays nickel back in passing situations.
With Kilgore out for the season, the 49ers plan to go with rookie center Marcus Martin, a third-round pick from USC, coach Jim Harbaugh said last week.