San Francisco 49ers defensive lineman Justin Smith hasn't missed a game in 11 years, but that streak could be in jeopardy this coming weekend.

The three-time Pro Bowl selection sat out a third consecutive practice on Friday with an elbow injury, with the Niners officially listing Smith as questionable for Sunday's pivotal NFC West showdown at Seattle.

Smith exited last weekend's 41-34 win at New England in the second half due to the injury. According to Comcast SportsNet Bay Area, the usually durable veteran was initially tagged as doubtful before being switched to questionable on the final report, but still figures to be a game-time decision come Sunday.

The 33-year-old enters Sunday's matchup having played in 189 consecutive regular-season contests. The only game Smith has sat out during his 12-year career was the opener of his rookie season of 2001, and that was because of a contract holdout with the Cincinnati Bengals.

If Smith is unable to go on Sunday, fourth-year reserve Ricky Francois would step into his place.

San Francisco's lone injury concern on the offensive side is wide receiver Mario Manningham, who's been inactive the last two weeks with a shoulder problem. The offseason acquisition is also questionable to face the Seahawks, though he's been able to practice on a limited basis throughout the week.