DE has bulging disks in back

As if San Francisco wasn't already in enough trouble, heading into Sunday's game against St. Louis minus its best passer, now the 49ers will have to face the Rams without their best pass rusher as well.

With quarterback Jeff Garcia already sidelined with a badly sprained ankle, San Francisco has now officially ruled out starting right defensive end Andre Carter, the third-year veteran who leads the team with 3½ sacks.

Bothered by two bulging disks in his lower back discovered during an MRI examination Thursday night, Carter will require at least two weeks of rest and treatment. The 49ers have a bye next week, so both Carter and coach Dennis Erickson hope the former first-round draft choice will be able to return to the field Nov. 17 against Pittsburgh.

Carter, 24, will receive an epidural injection on Monday and then will have to severely reduce his physical activity for a week to 10 days after that.

The loss of Carter means that the 49ers will shuffle their defensive front in an effort to create pressure against Rams quarterback Marc Bulger. Left end John Engelberger will move into Carter's spot on the right side and reserve Chidi Ahanotu will start now at the strongside end spot. Sean Moran will serve as the No. 3 end, likely backing up at both spots, and rookie Andrew Williams probably will make his regular-season debut.

The San Francisco defense ranks third in the NFL with 22 sacks and the 49ers tend to spread the wealth in rushing the passer. The rush scheme, though, revolves in large part around Carter, who is very quick off the ball and is a disruptive force coming off the edge. None of the other 49ers pass rushers possesses Carter's level of quickness.

Carter said he originally twisted his back in training camp, then aggravated it twice in regular-season games -- Sept. 21 against Cleveland and Oct. 19 against Tampa Bay. The former University of California standout, a first-round choice in the 2001 draft, said he grew up with a condition sometimes known as "swayback," and that puts some additional pressure on his lower back.