ST. LOUIS -- Mark Setterstrom was in street clothes for the St. Louis Rams' first nine games, a typical fate for a rookie seventh-round pick.

All of those weeks on the sideline were evidently well-spent, because he gave the team's battered offensive line a much-needed boost in Sunday's comeback victory over the 49ers. A patchwork unit kept Marc Bulger upright so he could lead the late-game drive that ended the Rams' five-game losing streak.

"When you're on your third center and starting a rookie at left guard and our tackle is out of position, there's certainly things they're not going to do as well," Bulger said. "I think they're doing an exceptional job."

Especially Setterstrom, who started every game in college during four years at Minnesota. Coach Scott Linehan said he graded out the highest on the entire line.

"That's pretty impressive," Linehan said. "He was a big factor in being able to run the football. That's the reason we drafted him, it's the reason he's here."

Setterstrom is the fourth player the Rams have tried at left guard. Richie Incognito started the opener at that spot before moving to center when Andy McCollum sustained a season-ending knee injury. Todd Steussie had eight starts before moving to left tackle when Orlando Pace was lost with a torn left triceps. Adam Goldberg started the fourth game of the season against the Lions when Pace was out with a concussion and Steussie had to fill in at tackle again.

A fifth player, Claude Terrell, was lost in training camp with a wrist injury after starting 10 games at left guard last season.

Patiently, Setterstrom added upper-body strength and worked on technique.

"I was just waiting for my chance," he said. "This first year is kind of a development process and I tried to soak up all I could.

"Obviously, I wanted to get out there but it wasn't frustrating."

Setterstrom got his first game action two weeks ago in a loss at Carolina with two series at right guard, once to get his feet wet and also filling in when Adam Timmerman was nursing a rib injury. That cameo merited his first career start against the 49ers.

Setterstrom is a much better run blocker at this stage of his career, and his work helped Steven Jackson rush for 121 yards. He's more raw protecting the passer, although his work helped limit the 49ers to two sacks of Bulger, who had been sacked seven times the previous week.

"He's really worked hard to get himself ready to play," Linehan said. "He played as good as any rookie I've been around in his first start, that's for sure."

The only linemen still in their opening-game spots against the 49ers were right tackle Alex Barron and Timmerman. Backup center Brett Romberg played his second NFL game, and first since 2004, after Incognito sprained his right foot and twice had to leave the game.

"It took a couple of plays, but when everybody was on the same page and we're all going down the field, it kind of smoothed out," Romberg said. "It was great.

"When we look back at it, we protected Marc pretty well and ran the ball extremely well."

Incognito expects to be back this week, although Timmerman was questionable.

"It came together real well," Incognito said. "We had a couple of guys hurt and we plugged guys in and they still played well."