Stephon Heyer is getting ready to play left tackle. And right tackle. Then again, he might not play at all.

"You don't know what will happen in the flow of the game, so you have to be free to go anywhere," he said. "Wherever they try to put me, I'm down for it."

Heyer isn't alone in his uncertainty as the Washington Redskins tinker with their offensive line while preparing to face the St. Louis Rams on Sunday.

Left tackle Trent Williams appears doubtful, having not practiced this week after hurting his left knee and a toe on his left foot in last week's loss to Houston. Left guard has been a rotation between Derrick Dockery and Kory Lichtensteiger. Right tackle Jammal Brown, who has been brought along cautiously after sitting out last season with a hip injury, could be forced to play an entire game on the artificial turf of the Edward Jones Dome.

"We're kind of missing out, maybe a little bit, on that cohesion that you get from the same group the whole game," Lichtensteiger said, "but we make up for it in effort and how we're playing so far."

Maybe so, but the running game, in particular, has been lacking. The Redskins are averaging only 2.7 yards per carry and have rushed for just 107 yards overall in their 1-1 start. With three new starters entering the season and a fourth now being rotated, only center Casey Rabach remains an every-down constant from last season's line.

"We are all learning a new offense and once everyone gets settled in there, things will take off," quarterback Donovan McNabb said. "It is unfortunate what happened with Trent. If he is not fully healthy, Stephon will be able to get in there and make some plays."

Heyer's first snap after replacing Williams against the Texans was a holding penalty that nullified a 22-yard reception on third-and-20 in a tie game late in the fourth quarter. It's not easy to commit a more untimely error.

A left tackle at Maryland, the fourth-year veteran has played 29 games at right tackle and eight on the left for the Redskins. His versatility helps keep him on the roster, despite his inconsistent efforts.

"A guy that can play three, four positions on the line is pretty useful," Heyer said. "I don't mind. One day I'll get a chance to have my own spot and stay home."

For now, though, it won't be easy replacing Williams, the No. 4 overall pick from Oklahoma who hasn't looked much like a rookie at all.

"Not having Trent hurts the team — period," running back Clinton Portis said. "I think Stephon is capable of picking up the slack. The guys around him have to elevate their play. All of us have to elevate their play until we get Trent back."

The Redskins have a couple of options if Williams doesn't play. Heyer could be plugged in at left tackle, or Brown could move from the right side to the left side, with Heyer taking right tackle. Brown said he's still getting used to the right side after playing three seasons at left tackle for New Orleans before sitting out last year with the injury.

Offensive coordinator Kyle Shanahan said Brown took some snaps at left tackle on Wednesday.

"Playing (right tackle's) a little different for me after not being over there for five years," Brown said. "It's just making sure of the footwork and things like that."

As for the left guard situation, that's been a surprise. Lichtensteiger thought he was going to be a backup this season, so it was news to him when coaches told him the night before the opener that he and Dockery would each play every other series.

Coach Mike Shanahan said the rotation will continue until one player earns the job.

"It's been very close, a very tight race," Shanahan said. "We want to give both guys a chance to win that position."

Notes: S Kareem Moore says he's ready to play Sunday after missing the first two games following knee surgery. "I'll be a little rusty," Moore said, "but, hey, got to get in there and clean it off." ... WR Anthony Armstrong (groin), S Chris Horton (ankle) and DL Anthony Bryant (head) didn't practice. ... DL Albert Haynesworth fully participated in practice as he attempts to return from a sprained ankle.