ASHBURN, Virginia -- The Washington Redskins' starting offensive line spent most of Thursday’s practice in a bad position: watching everyone else practice. That’s not what the Redskin need, but it is the reality of their situation.

The lone starter able to practice: left guard Shawn Lauvao. That could lead to a lot of shuffling for Sunday’s game vs. the Dallas Cowboy -- or, at the least, a lot of walking wounded. And that could alter what the Redskins do offensively.

The injured starters include left tackle Trent Williams (knee), center Spencer Long (quads), right guard Brandon Scherff (knee) and right tackle Morgan Moses (ankles). Of this group, Redskins coach Jay Gruden said he was most concerned about Long’s availability. Indeed, he was the one player not on the field working with the trainers during the portion of practice open to the media.

Williams’ situation isn’t new and he said he’ll keep playing on his knee until he can’t go anymore. But it does impact his game, particularly the ability to react to lateral movement or drive guys off the line. Moses struggled with his ability to move as well, getting beat a few times against the Eagles when he was unable to react to change-of-direction.

If Long can’t play, then rookie Chase Roullier would start. He played in the second half at guard against the Eagle after Scherff went out.

“He’s got a good demeanor,” Redskins quarterback Kirk Cousins said. “He can anchor well and he’s only going to get better. As a rookie is it a challenge? Sure, but we feel good about his potential and we just have to work through the growing pains.”

If Scherff also can’t play, then the Redskins could start undrafted rookie Tyler Catalina. They also have newly-signed veteran Tony Bergstrom and T.J. Clemmings, who has worked at each position but center.

But losing Scherff, combined with an ailing Williams, impacts the screen game. Both players move well in space, helping to create better lanes for running back Chris Thompson in the open field. Without them, the screen game changes, especially against a speedy linebacker group such as Dallas’. The screen has been a big part of Washington’s offensive success, so a drop-off there will result in needing to attack in different ways.

Also, backup tackle Ty Nsekhe did not practice but worked off to the side -- light jogging and agility drills. If he were healthy, the Redskins could rest Williams or Moses. But Nsekhe is still recovering from his core muscle injury.

Linemen always point to familiarity with one another as a key reason for success. Sunday, the Redskins will have to hope that success stems from others being ready to fill in.

“It’s difficult but it’s something these guys have to be ready to do,” Gruden said. “Eventually your number is going to be called and you have to prepare that way.”

It’s not just the line that’s hurting. Linebackers Preston Smith (groin) and Mason Foster (shoulder) were limited as were safeties Deshazor Everett (hamstring) and Stefan McClure (hamstring/knee) and corners Josh Norman (rib) and Fabian Moreau (hamstring).

That lengthy list led to Gruden altering practice plans. They worked in shells instead of pads Thursday after having just a walk-through Wednesday.

They might have to have more than just a walk-through Saturday; perhaps, Gruden said, they’d have to jog through plays that they didn’t rep enough of during the week.

“It’s frustrating but it’s pro football and something we have to deal with,” Gruden said. “It’s just unfortunate.”