ST. LOUIS – One day after insisting he’d stick with Marc Bulger, St. Louis Rams coach Scott Linehan benched his banged-up quarterback.

The winless Rams will go with backup Gus Frerotte on Sunday against the Arizona Cardinals, Linehan said Wednesday. Frerotte and Bulger, who has been ineffective while playing with two broken ribs, both got the news Tuesday from the coach and the switch was made public before practice Wednesday.

Linehan also will return to play-calling in an effort to wake up a dormant offense that has scored only two touchdowns, yanking duties from offensive coordinator Greg Olson. Olson was Linehan’s first hire when he got the job last year, and will move to the coaches booth, where he’ll assist the head coach.

Linehan said sitting Bulger was his call after reviewing the last three games, and not a decision made under pressure from superiors.

“Any theories or anything said out there are absolutely not true,” Linehan said. “I look forward to a healthy Marc Bulger getting back in the lineup as soon as possible.

“It’s obvious to me there is something genuinely wrong, and I knew there was.”

Bulger, a two-time Pro Bowl player, signed a six-year, $65 million contract extension in training camp. He has thrown four interceptions the last two weeks and was 11-for-24 for 114 yards and an interception in Sunday’s 35-7 loss to the Cowboys, the first sub-50 percent passing game of his career.

All season, Bulger has insisted he was healthy enough to play. It’s unclear how much time Bulger will need to heal after injuring the ribs while being sacked six times in the second week of the season against the Panthers.

“I was never going to pull myself out, I know that much,” Bulger said. “It’s real easy to play hurt when you’re winning, but it’s just not in me to pull myself out when we’re 0-4.

“It was going to have to be the coaches pulling me out, and that’s what happened.”

Bulger had not been aware of Linehan’s endorsement on Monday. He did not argue his coach’s about-face.

“I’ve tried for a couple of weeks,” Bulger said. “He had enough of me telling him I was OK.”

The 36-year-old Frerotte started 15 games in 2005 for Miami, where Linehan was the offensive coordinator at the time. Bulger will be Frerotte’s backup against the Cardinals (2-2) on Sunday.

“He said, ‘We’re going to switch things around and let’s go, let’s see what you’ve got,”‘ Frerotte said. “I said, ‘I’m ready.’ We’ve made several changes this week and hopefully it’ll show up on Sunday.”

Frerotte also had success stepping in for injured Daunte Culpepper with the Vikings in 2003 when Linehan was the offensive coordinator there. That led to his deal with the Rams.

“He’s a proven quarterback,” Linehan said. “Even better yet, he understands his role and he knows what he’s being asked to do.”

Bulger has been playing behind a patchwork offensive line decimated by injuries. Left tackle Orlando Pace and guard Mark Setterstrom are out all season with injuries, and guard Richie Incognito has yet to play because of a high ankle sprain, although he’s expected to return on Sunday.

Linehan likened his decision to take over play-calling again to a “lineup change.” He expects to call plays the rest of the season, but knows, given the Rams’ injury-riddled start, not to promise anything.

“Get me through this week and you can ask me a whole new set of questions next Monday,” Linehan said.