By Jim Thomas
Of the Post-Dispatch
It may be for just one Sunday. It may be for the next 10 years. Or somewhere in between.

But Steven Jackson is replacing the great Marshall Faulk at running back Sunday against San Francisco.

"I'm very excited," Jackson said Friday. "This is something I've been waiting on since I joined this organization. I feel there's a lot of pressure on me right now, but I think I'm going to stand tall, and I'm going to handle it pretty well."

Pressure? Well, Faulk is a certain Hall of Famer and arguably the best all-purpose back in NFL history. As for the Rams as a whole, they've reached a critical stage of the season. At 5-6 and losers of four of their last five contests, they desperately need something to jump-start them out of their funk and into the playoffs.

Can Jackson help provide that spark?

"We need a change-up, and I'm going to have an opportunity to do that," Jackson said. "To give this offense and this team a different approach."

At 6 feet 2, 231 pounds, Jackson is a different style back than Faulk. He's 20 pounds heavier and more of a power runner. But he's no slowpoke. Jackson has shown an ability to turn the corner and the quick feet to jump-cut and change directions quickly.

He was a workhorse in college at Oregon State, the kind of back who got stronger as the game progressed.

"We're all kind of anxious to put him in that kind of a role, and see what he'll do here," coach Mike Martz said.

Jackson believes he's up to the task.

"That's my style of play," Jackson said. "I'm willing to get those knickknack yards at the beginning of the game. But then as the game progresses, I wear down the defense. That's where my big gains come. So as long as we can stay in the ballgame, and we can run the ball successfully, I think that's something that can very well happen."

No, Jackson doesn't lack for confidence. He's self-assured, but not ****y. And he has been respectable of Faulk all season, taking spot duty when it comes and waiting for his time.

"It's been difficult," Jackson said. "At the same time, it's given me a chance to get my feet wet. I've been able to participate in all the games this year, so it's not something where I'm coming in with cold feet.

"I know what to expect. I had a good game against these guys earlier this year, so I'm going into a situation that's fairly easy for me."

Easy, as in comfortable. Jackson carried 10 times for 46 yards when the Rams defeated San Francisco 24-14 on Oct. 3, scoring his first NFL touchdown. During that Sunday night game, San Francisco cornerback Mike Rumph made the mistake of trying to bring down Jackson in the open field with an arm tackle.

Rumph suffered a season-ending broken arm. Jackson says he doesn't remember that play. Rest assured, the San Francisco secondary remembers. They might have flashbacks every time Jackson turns the corner with a full head of steam.

"I'm really looking forward to seeing how he handles this for four straight quarters," wide receiver Torry Holt said. "It'll be different. I know last year when we played Pittsburgh, Arlen (Harris) had 33 totes."

Harris actually had 34 carries for 81 yards and three touchdowns that day. Faulk was out with knee and hand injuries at the time.

"I think one of the things Arlen asked Marshall was, 'How are you doing this every single week?' " Holt recalled. "So it'll be challenging for Steven. It'll be good for him.

"It'll be some new legs. Some fresh legs. He'll be excited, enthused. He'll be running like a maniac, which will be good for us."

The Rams certainly need some kind of pick-me-up. In their recent losses to Miami, New England, Buffalo and Green Bay, they have been outscored by an average of 38-18.

Until stabilizing against Green Bay, special teams has been a disaster area. The offense has been a tease, moving the ball successfully against just about everyone, but not converting yards into points. And the defense just can't stop the run.

As a result, the mood of the team is a combination of frustration, anger and embarrassment.

"We haven't lost like this in a while around here," quarterback Marc Bulger said. "But hopefully we can turn things around these last five weeks and make a run."

For his part, Martz has tried just about everything to get his team back on track. From live tackling in practice . . . to cutting veteran punter Sean Landeta . . . to a variety of lineup changes on defense . . . to exhorting younger players to pick up the pace.

This week, sensing that his team is playing tight, Martz is simply asking the players to have fun and play with passion.

"The passion that you have playing this game sometimes gets sidetracked and pushed aside," Martz said. "You've got to do whatever you can to let that passion come back - in how you approach and play this game. It is legal to have fun and play professional football."

Perhaps Jackson can help put a smile back on their faces.