Right guard Randy Thomas will undergo surgery this week to repair his injured triceps, head coach Joe Gibbs said.
Thomas underwent an MRI on Tuesday, and the results confirmed that there was a tear.
As to Thomas's availability for the remainder of the season, Gibbs said: "We're just going to have to evaluate after the surgery what we think would be the time frame for him coming back."
It's likely that Thomas will be sidelined for a significant period of time.
If it's determined that Thomas could return post-surgery by November or December, then the team could opt to keep him on the active roster so he is available for the stretch run.
If Thomas is placed on injured reserve, then his season would be finished.
Vice president of football operations Vinny Cerrato said on Redskins Radio on Tuesday morning that the team will work out three center/guards on Wednesday morning.
Thomas suffered the injury in the first quarter of Monday night's game against the Philadelphia Eagles.
Ten-year veteran offensive lineman Jason Fabini stepped in for Thomas during Monday night's game. Fabini joined the Redskins last offseason as an unrestricted free agent.
Asked for the team's plans at right guard, Gibbs said: "We'll go just the way we did in the game. Jason stepped in as a real veteran. I felt like he did a great job for us. He's very conscientious, very smart, and he worked extremely hard to make the team.
"I think it showed that he has been around, played a bunch of games, can step in and not panic."
Late in the first half, Fabini did struggle with several false start penalties, but that could be attributed to the road environment, some rustiness and unfamiliarity with Jason Campbell's calls at the line of scrimmage.
Thomas is the second offensive lineman the Redskins have lost in two games.
In Week 1, the Redskins lost right tackle Jon Jansen to a fractured dislocation of his ankle. Jansen underwent surgery last week to repair the injury. He is sidelined for the remainder of the season.
Jansen was replaced by Todd Wade in the lineup.
Wade and Fabini provide reliability as veterans, but Jansen and Thomas offered tangible on-field leadership that will be missed.
"It was almost like, I couldn't believe it," Gibbs said. "Two weeks in a row it happened. You hate it for [Jansen and Thomas]. Both of those guys are dynamic leaders in the locker room and they come to play. Our players all know it.
"I told Jon this morning that we want him here every minute. It's the same thing with Randy, whenever we determine how long he'll be out. They're certainly a big part of what we do here--both of them. We want to keep them here with the team, in the meetings.
"They've made a huge investment in their life into this football team, and so we want them to be here."