SANTA CLARA -- Because Justin Smith is one of the NFL's most remarkable iron men, he deserves the benefit of the doubt. But evidence mounted Friday that the defensive lineman's streak of 185 consecutive starts is in jeopardy as the 49ers prepare for their NFC West showdown with the Seattle Seahawks.

Smith, a three-time Pro Bowl selection, did not practice Friday, capping a week in which he was sidelined by an undisclosed elbow injury. The 49ers listed him as questionable on their injury report.

Ricky Jean Francois sounded so certain that he would fill in at right defensive tackle that at one point he called it "just another start. Ain't going to be sitting on the bench. ... So the preparation this week was a little different."

But the 6-foot-3, 295-pounder later clarified that coaches had not officially informed of his status. "So it might still be in the air," he said.

If Smith does sit out, it would end the third-longest starting streak in the NFL. The only players with longer current streaks are Tampa Bay Buccaneers defensive back Ronde Barber (213) and Washington Redskins linebacker London Fletcher (197).

Smith, 33, has not missed a start since 2001, his rookie season with the Cincinnati Bengals.

"He's impressive. Not only to play in the line, but to play the way he does. He plays every single play," 49ers offensive tackle Joe Staley said.

In what might have been nothing more than gamesmanship, the 49ers upgraded Smith's status from doubtful to questionable over the course of a few hours Friday despite the fact that the lineman never took the field.

Coach Jim Harbaugh, who is loath to discuss injuries, was predictably tight-lipped, saying only that Smith did a lot of "rehab, strengthening and conditioning."

The 49ers (10-3-1), who have clinched at least a wild-card spot, could win the NFC West by beating the Seahawks (9-5) on Sunday night in Seattle.

The Seahawks have won three in a row and five of their past six games. They have scored at least 50 points in consecutive games. Led by running back Marshawn Lynch and quarterback Russell Wilson, the Seahawks are 6-0 at home.

Francois, a fourth-year player from LSU, earned strong reviews from the 49ers coaching staff after filling in for an injured Smith in the second half against the New England Patriots last week. He sacked Tom Brady on a third-and-15 play in the fourth quarter.

"It was fun playing against him," Francois said Friday. "It was a big steppingstone for me to play in a game like that and have a tremendous sack at the end of the game that actually made a difference."

Francois vows to be ready if needed.

"I'm just trying to show my coaches that I'm a starter, that I'm someone you can trust when the times get really tough," he said.

  • Lynch has at least 100 rushing yards in six of his past eight games. He also has two consecutive 100-yard games against the 49ers (103 on Oct. 18 and 107 last Christmas Eve.)

    "The last two years, he's the toughest back we've gone against,'' 49ers defensive coordinator Vic Fangio said. "Our guys have a lot of respect for him. But he's doing it against everybody. He's got almost 1,400 yards already."

  • The 49ers and the Patriots proved to be must-see TV last week. The Sunday Night Football game on NBC drew 23.2 million viewers, up 40 percent from last year's Week 15 game (Ravens-Chargers, 16.6 million).

  • Wilson has been dynamite at home, completing 61.3 percent of his passes with 12 touchdowns, one interception and a 118.4 passer rating at CenturyLink Field. He is the first rookie since the 1970 merger to start and win his team's first six games at home.

  • With a victory Sunday, Harbaugh would become the eighth coach to win a division title in each of his first two seasons. The others are Chuck Knox (five times, 1973-77), Ted Marchibroda (three, 1975-77), Red Miller (1977-78), George Seifert (1989-90), Barry Switzer (three, 1994-96), Mike Tomlin (2007-08) and Jim Caldwell (2009-10).

  • The 49ers have scored at least 30 points in six games this season, a feat they last accomplished in 2003.

    Contact Daniel Brown at dbrown@mercurynews.com.

    Sunday's game
    49ers (10-3-1) at Seattle
    (9-5), 5:20 p.m. NBC