Defensive lineman Phillip Daniels re-aggravated his groin injury during Sunday's game against Detroit and his status for next week is uncertain, team officials said.
Daniels was scheduled to have a second MRI on his groin on Monday. The results were expected to be evaluated on Tuesday.
Daniels had only recently returned to action after missing Weeks 3-6 due to the groin injury. He initially suffered the groin injury in the Week 2 game against the New York Giants.
"Hopefully it won't be a major deal," Gibbs said. "We need to get healthy. We lost two guys [Andre Lott and Chad Morton] last week and hopefully not Phillip this week. We have a lot of guys sitting out right now. It's extremely tough on our football team."
Defensive linemen Ron Warner and Demetric Evans split time in place of Daniels during Sunday's game.
Another defensive end, Renaldo Wynn, was wearing a protective boot at Redskins Park on Monday after spraining his ankle in the Detroit game. Although the injury is not believed to be serious, it is expected that Wynn will be limited in practice some this week.