Steven Jackson is getting a light workload in the preseason to help his surgically repaired back for the regular season, and he dressed but didn't play a down in the St. Louis Rams' opener.

The Pro Bowl running back's absence can't be helpful in the development of No. 1 draft pick Sam Bradford, who got sacked four times in a 28-7 loss to the Minnesota Vikings on Saturday night.

The Rams had only 150 yards total offense and got their lone touchdown on a 93-yard punt return by Danny Amendola.

"I think it goes without saying that when your best player is on the sideline, the unit he plays with isn't going to feel the same," coach Steve Spagnuolo said Sunday. "We know what Steven can do, but when he's not in there which could happen in the regular season, the play can't go down.

"We've got to be just as effective."

That puts the onus on an offensive line that's been a focus of the rebuilding effort, but allowed six sacks. Right tackle Jason Smith, who's been hampered during camp by a fractured toe, struggled with his mobility, and guard Jacob Bell missed the game with a hamstring injury.

Spagnuolo said half of the sacks were because of faulty technique, the other half missed assignments. Of Smith: "He just needs 1,000 repetitions."

Jackson carried the offense on a 1-15 team last season. Despite playing the last third of the season with a herniated disk that kept him off the practice field most of the time, his 1,416 yards rushing was the second-best of his career.

Spagnuolo said Jackson might get a few snaps next Saturday at Cleveland, but said the team would "tread lightly." The Rams mustered 33 yards with a 2.5-yard average in the opener and were lead by Keith Toston, an undrafted rookie who had 16 yards on four carries.

Bradford completed four of his first five passes, but only two of his last eight while getting battered a bit by the Vikings' second-team defense. Bradford said after the game that the back felt "great" and Spagnuolo said the quarterback was not on the injury report.

Spagnuolo liked Bradford's zip on the ball on a couple of throws, particularly on an 18-yarder to Laurent Robinson for a first down on his opening series and on a sideline pattern that was incomplete at the start of the second half. He was most impressed with the rookie's ability to think on his feet.

"He made two really, really good decisions to dump the ball to the back," Spagnuolo said. "I know that's not the most glamorous play, but he made quick decisions. To me that was one of the most positive things he did, he made really quick decisions."

Bradford, who worked out of the shotgun formation at Oklahoma, had some issues on the center snap along with occasional communication woes. The Vikings also batted down a handful of passes, and one of Spagnuolo's biggest disappointments was the Rams stalling at the Minnesota 36 on Bradford's first drive, failing to pick up a yard on third or fourth down.

"I felt like I did some good things," Bradford said. "I felt like I did some things not so good, but that's what the preseason is for. I'm sure we'll find a lot of things to work on."

Bradford is a backup for now behind A.J. Feeley, who also struggled. Feeley was 3 for 6 for 19 yards and narrowly avoided interceptions on two passes that could have been returned for touchdowns.

"As a quarterback, you've got to be productive and move the team. If that doesn't happen, it's always on you," Feeley said. "That's how I look at it.

"We're not where we want to be, that's obvious."

The most significant injuries were to cornerbacks Jerome Murphy and Brandon McRae, who both sprained left ankles and might be out for a while. Murphy was a third-round pick this year.

Several players who missed the Vikings game were set to return to practice, including Bell, cornerbacks Ron Bartell and Bradley Fletcher and wide receivers Brandon Gibson and Mardy Gilyard.