SANTA CLARA, Calif. (AP) -- New blood is helping the San Francisco 49ers' defense play some of its best football of the young season.
The Niners got some standout efforts from reserves asked to take on expanded roles during last week's 35-11 rout of the St. Louis Rams, a performance that vaulted San Francisco to No. 4 in the NFL's defensive rankings.
With All-Pro linebackers Patrick Willis and Aldon Smith and nickel cornerback Nnamdi Asomugha missing that game, the 49ers limited the Rams to 188 yards to end a string of subpar outings to begin the season. San Francisco allowed an average of 28 points and 337 yards in its first three games.
Middle linebacker Michael Wilhoite, who replaced Willis in the heart of the defense, said it was all about urgency after San Francisco started the season 1-2.
''The whole thing is, it's not about who's out there,'' Wilhoite said Friday. ''This organization produces good players whether it's the starting guy or the backup guy. We approach the game hungry, desperate, willing to do anything to win. That's how our mindset is now. We're desperate to win. When you're willing to do anything to get the job done, you're going to get it done.''
Wilhoite, who had five tackles against the Rams in his first NFL start, wasn't the only backup getting the job done.
Dan Skuta and rookie Corey Lemonier combined to do a fine job replacing Smith's pass-rushing presence on the edge, and Tramaine Brock made some key plays in pass coverage in place of Asomugha.
With Willis and Asomugha still questionable to return this week, and Smith still out indefinitely, the 49ers (2-2) will be asking their supporting cast to step up again Sunday when they host the Houston Texans (2-2) and the league's fifth-ranked offense.
Stepping up hasn't been a problem for these guys.
''Guys just come in,'' said Lemonier, San Francisco's third-round draft pick this year. ''There's no void to fill. It's just the preparation we have. You go out and do your job when your name is called.''
Lemonier contributed a career-high three tackles and also provided good pressure from the edge as the 49ers harassed St. Louis quarterback Sam Bradford with a season-high five sacks. Lemonier also displayed the ability to drop into coverage and batted away one of Bradford's passes.
Skuta got the starting assignment in place of Smith, who led the NFC with 3.5 sacks after two games but left the team Sept. 23 to deal with personal issues. Skuta shared snaps with Lemonier and, like Wilhoite, continued to perform his regular duties on special teams. Wilhoite and Skuta combined for three special teams tackles against the Rams.
''We just went in there and did our part,'' Skuta said. ''The whole defense played great. On the board in our (locker room) it says, 'Get Back to Basics,' and that's kind of been the battle cry for the year. I feel like that's what we did and everybody just played good, and if everybody plays together you get outcomes like that.''
Brock had three tackles and two passes defensed, one of which became a pivotal play.
With the 49ers holding a 7-3 lead and the Rams driving in San Francisco territory late in the second quarter, Brock ran stride for stride with tight end Jared Cook down the sideline and tipped away Bradford's pass near the goal line. It was intercepted by safety Donte Whitner in the end zone, and San Francisco then drove 80 yards for a touchdown that put the Niners in control seconds before halftime.
Defensive coordinator Vic Fangio said he expects Brock to be in the same role against the Texans. The same is likely for Skuta, Lemonier and Wilhoite, whom coach Jim Harbaugh on Friday called a ''trusted agent'' while subbing for Willis, the team's six-time All-Pro and defensive leader.
''As soon as we got in the game last week, it just really flowed with us and we did a pretty good job with it,'' Lemonier said. ''Now we're focused on this week. The whole mindset is to go out and do your job, so we'll be ready.''
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