Justin Smith questionable for 49ers

Jean Francois has started at both nose tackle and left tackle in San Francisco's 3-4 defensive scheme since being drafted by the 49ers in 2009. Smith's presence on the right side hasn't given him many opportunities there.

Jean Francois has become a regular part of San Francisco's defensive line rotation that includes McDonald and starting nose tackle Isaac Sopoaga. His 34 tackles this season already are a career high, and Jean Francois had 11 tackles over a two-game stretch in September which included one start in place of an injured Sopoaga.

"I'm just trying to show my coaches that I'm someone you can trust when the times get really tough," Jean Francois said. "You can put me in and the ball will never drop. That's the biggest thing, just making sure the ball keeps rolling whether it's Ray out or Justin out."

Smith is a key cog in San Francisco's third-ranked rushing defense that will collide Sunday with Seattle's third-ranked rushing offense. Smith's 130 tackles rank third on the team behind All-Pro linebackers NaVorro Bowman and Patrick Willis.

But if Smith's not there, the 49ers are confident Jean Francois can hold the line.

"Ricky's a very good player who could start for a lot of football teams in the NFL," said 49ers Pro Bowl offensive tackle Joe Staley, who lines up against both Smith and Jean Francois in practice. "He fits the scheme really well and he knows exactly what he's doing. Obviously, Justin is Justin Smith, one of the best players in the NFL. But Ricky does a terrific job going in there, and if he's in there we expect him to do great things for us."