The San Francisco 49ers are closing in on an NFL record but to get there they will have to shut out the last running back to score a touchdown against them.

The Niners host the St. Louis Rams on Sunday at Candlestick Park and Steven Jackson, the Rams’ running back, is the last player to score a rushing touchdown against San Francisco’s defense. That was in Week 16 of last season.

Right now, the Niners are five games away from becoming the first team in league history to not allow a rushing touchdown in a 16-game season, according to Matt Barrows of the Sacramento Bee. The record for fewest rushing touchdowns allowed in a 16-game season is four.

What other backs will take a crack at the 49ers this season? Arizona’s Beanie Wells, Pittsburgh’s Rashard Mendenhall, Seattle’s Marshawn Lynch and Jackson again in Week 17 round out the lineup of backs. It will be difficult but the defense has done a terrific job to point.

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Brad Biggs covers the Bears for the Chicago Tribune