Steven Jackson has been a one-man show in the St. Louis backfield for the better part of a decade.
Since the 2005 season, Jackson has rattled off seven straight 1,000-yard seasons, the longest active streak for any back in the NFL. But the Jeff Fisher-led coaching staff has changed things up for Jackson and the Rams offense in 2012.
There's a new tailback in town and the Rams think the backfield is big enough for both of them.
Rookie Daryl Richardson has emerged from relative obscurity to become Jackson's complement in the backfield this season.
Not familiar with Richardson's past playing career? Neither was 49ers defensive coordinator Vic Fangio until he popped in the game tape of the St. Louis offense.
"I don't know what his college background was or why he lasted that long (in the draft), but this guy's a talented back," Fangio said. "He's not on the big side with his size, but he runs well, he's quick, he's fast. And on contact he brings a little bit of a good pop to him that you wouldn't think for a guy that's under 200 pounds."
The 5-foot-10, 196-pound Richardson was a seventh-round selection out of Abilene Christian, part of a three-back draft class by the Rams in April. Richardson has beat out second-round pick Isaiah Pead and sixth-round draftee Terrance Ganaway to become Jackson's backup so far this season.
Looking at the numbers, perhaps Richardson has helped the Rams evolve into a two-back team this year. Jackson has 108 carries to Richardson's 62, but the veteran's marks of 3.7 yards per carry and 13.5 attempts per game are the lowest since his rookie year in 2004. Meanwhile, Richardson is averaging a robust 5.4 yards per carry this year.
"I've been very impressed with him," Fangio said of the first-year player. "And they (the Rams) have been, too, because he's been getting more and more playing time."
Still, the 49ers aren't looking past Jackson. 49ers defensive captain Joe Staley is used to his two annual meetings with the talented tailback and still considers him to be a threat every time he touches the ball. At 6-foot-2, 240 pounds with top-notch speed, Jackson is a rare breed in today's game.
"Having to go against him twice a year, I'm like, 'Man, this dude is big,'" Willis said. "He's a great competitor and each time we play against him it's always great competition."
Year two of the Fangio-led defense has been very similar to the first year. It's tough to run on the 49ers and even tougher to score.
Through Week 9 action, San Francisco ranks first in NFL scoring defense (12.9 points per game), second in total defense (271.4 yards per game) and fifth against the run (87.4 yards per game), giving up just two rushing scores in the process.
As such, the 49ers have to be considered one of the top defenses in the game. Just not No. 1 in the eyes of President Barack Obama.
Willis was watching "Monday Night Football" earlier this week when Obama declared Chicago's defense to be the best in the league.
"He's our President, so you can't say much about who he thinks is the best," Willis said with a laugh. "It's his hometown so he has every right to say them. But I guess we'll see when it's all said and done."
The 49ers are in the midst of 23-day span that features just one football game, but have worked hard to stay sharp throughout the bye week. If the defense's effort on Sunday is anything like it had against the Cardinals in Week 8, the 49ers should be in good shape.
San Francisco limited its division foe to 7 rushing yards, tying a franchise record, as Arizona abandoned the run altogether in the second half.
"This week is a big week for us," Willis said. "We have to make sure we're getting back out there with an extra emphasis on getting back into it; making sure we're not easing back into it, we're hitting the ground running. We have the guys here who know what it means and understand what we have to get done."
The 49ers swept the Rams in the season series last year, but the dynamic of the NFC West showdown on Sunday will be different with Sam Bradford lining up under center. The Rams quarterback missed both games against San Francisco in 2011, but will be counted on to lead the St. Louis offense this time around.
"He's a good quarterback," Willis said. "He's a smart quarterback, very, very tough and he has a great arm. We most definitely have to make sure that we get after and not let him stay in the pocket and make the throws that he needs to make."