ST. LOUIS - A 49ers defense missing its spiritual leader and its top pass rusher seemed susceptible to slipping Thursday in St. Louis. Instead it had its most dominant effort of the season by far, forcing 11 Rams punts, two Rams turnovers and holding them to a paltry 18 rushing yards.
"If a link gets taken out of the chain, somebody needs to step up," said linebacker NaVorro Bowman, who led San Francisco's defensive effort with two sacks and three tackles behind the line of scrimmage.
Inside linebacker Patrick Willis sat out the game with a groin injury. Aldon Smith, meanwhile, is seeking treatment after crashing his truck and being arrested for DUI last week. Despite not playing, Smith increased his sack total when the NFL ruled that he, not Justin Smith, took down Colts quarterback Andrew Luck on Sunday. Aldon Smith now has 4 ½ sacks to lead the 49ers.
Dan Skuta replaced him in the starting lineup rookie Corey Lemonier entered in obvious passing situations. The 49ers sacked St. Louis' Sam Bradford five times and hit him an additional eights times. Ahmad Brooks had 1 1/2 sacks. Safety Donte Whitner grabbed his first interception of the season after he gathered in an end-zone pass from Bradford that had been tipped by Tramaine Brock, who was filling in for injured Nnamdi Asomugha.
It could have been even more one-sided. Whitner also dropped an easy interception - the deflection was caught by the Rams - while Bowman let what would have been an interception and touchdown return slip through his hands.
Michael Wilhoite made his first-ever start in place of Willis. Wilhoite, who filled in during the exhibition season after Willis broke his hand, finished with five tackles.
Wide-receiver shuffle - Hoping to spark a slumbering offense, the 49ers gave rookie Quinton Patton, not Kyle Williams, the nod as the No. 2 wide receiver against St. Louis. Patton, however, suffered a foot injury after just one catch for zero yards and did not return. Williams resumed his role and finished without any catches.
Meanwhile, Jon Baldwin made a solid debut as a 49er, catching a 14-yard pass on third-down in the third quarter. The 49ers swapped A.J. Jenkins for Baldwin, a former first-round pick by the Chiefs, last month. He had a second catch for four yards later in the game. "I've got a good feeling about him," Harbaugh said of Baldwin.
Baldwin had been inactive for the first three games. Jenkins, who's been active for every game this season, has one catch for six yards for the Chiefs.
Just for kicks - When the 49ers forced a Rams punt late in the first half, they opted for a seldom-seen play with four seconds remaining - a free kick from their own 39-yard line. Kicker Phil Dawson said it's a situation the 49ers prepare for. "It's a little, unknown rule that a lot of people aren't familiar with," kicker Phil Dawson said. "Our sideline definitely was prepared for it and we thought we'd give it a try."
The 49ers lined up as if they were kicking off but had Andy Lee hold the ball for Dawson. Had the 71-yard attempt been good, it would have been worth three points. The attempt was short and too far to the left, and the Rams returned it out of the end zone for a short gain to end the half. Dawson, who had made seven straight field goals from 50 yards and beyond, was wide right on a 53-yard try on the 49ers' opening drive.
Staley still standing - Harbaugh said the 49ers "dodged a bullet" when starting left tackle Joe Staley went down with 1:50 remaining and had to be helped off the field. A few minutes later Staley emerged from the X-ray room on his own without a limp. "He's going to walk it off," Harbaugh said.
Staley later tweeted: "I'm good. And I scream like no dude should ever scream lol my bad."
Both guard Mike Iupati and cornerback Tarell Brown also received X-rays. Neither injury is considered serious.
49er debuts -- Thursday was the first time time several 49ers, including running back LaMichael James, were in uniform this season. James, the team's second-round draft choice a year ago, suffered a knee injury in the exhibition season finale and had been on the injury report since. He carried three times for zero yards.
James was the team's primary punt returner in the preseason, but Williams handled that role on Thursday. James did line up as the team's kick returner. However, the initial kickoff resulted in a touchback; the only other one was an on-side kick.
Linebacker Nate Stupar and cornerback Darryl Morris also made their debuts. Stupar had two special teams tackles; Morris had one.
-- Matt Barrows