Redskins coach Jay Gruden said Allen will visit with noted foot specialist Dr. Robert Anderson to determine the severity of the injury. Gruden said Allen would "hopefully" miss only three to four weeks, though they'll know more about his absence after he visits Anderson.
Allen isn't the only injury concern for Washington. Cornerback Bashaud Breeland sprained his left MCL, but Gruden said he could play Monday, Oct. 23, at Philadelphia. Corner Josh Norman did not play vs. San Francisco on Sunday because of a fractured rib, but Gruden said he'll increase his exercise and running and will be re-evaluated midweek. Gruden said Norman could be ready for the Eagles game.
It's a tough time for the Redskins to suffer key injuries as their next five games are against Philadelphia, Dallas, Minnesota, New Orleans and Seattle.
The Redskins also dealt with injuries at safety during Sunday's 26-24 win over San Francisco. Montae Nicholson left with a shoulder injury before returning, and Stefan McClure suffered a hyperextended left knee. Safety Deshazor Everett already was out with a hamstring injury; he's expected to practice this week. Also, Gruden said the team will consider removing safety DeAngelo Hall from the physically unable to perform list this week or next, though he would be unable to play until the following week vs. Dallas.
On Monday, the Redskins worked out corner Nolan Carroll, cut by Dallas earlier this month. But a source said the Redskins aren't yet ready to add anyone until they know more about Breeland's status. Two years ago, Breeland was expected to miss four to six weeks with an MCL injury, but he returned in three weeks.
"Breeland's always been a fast healer," Gruden said. "He's like Gumby."
Also, the team might hold off on signing another defensive back in case they need to make a roster move at kicker. Dustin Hopkins has a right hip rotator muscle strain and might not kick vs. the Eagles. The Redskins will work out kickers Tuesday, just in case. The one bit of positive injury news for Washington: Running back Robert Kelley, who did not play Sunday because of a sprained ankle, is expected to practice this week.
Allen, the 17th pick in the 2017 draft, had been a key part of Washington's defensive line. He'll be replaced by second-year lineman Anthony Lanier, who earned a roster spot last season as an undrafted free agent. He's been inactive for the first five games this season. Lanier played in four games last season. Gruden said Lanier continues to improve his strength and has good length; he is 6-foot-6 with long arms.
But Allen played with a savviness the coaches liked. He has started in the nickel package and has averaged 30 snaps per game. Allen has only one sack, but he has consistently applied pressure and has helped collapse the pocket, enabling the edge rushers to record sacks.
"Just playing the position like a veteran," Gruden said of Allen. "He's a young player, but he plays it like a veteran. He has great fundamentals, great idea of run-pass and how to get off blocks. He has strong hands and he was getting a consistent pass-rush push. Just all-around, he's played well."