Detroit Lions rookie cornerback Darius Slay has a torn meniscus in a knee that was injured in practice this week, according to ESPN.
Slay is listed as doubtful for Sunday's game against the Philadelphia Eagles. He was injured Thursday and is reportedly considered week-to-week.
Lions coach Jim Schwartz said Friday it was a "freak" injury that occurred during a non-contact portion of practice.
Slay, who was drafted in the second round of this year's draft out of Mississippi State, has 27 tackles and four pass breakups.
After starting the first two games of the season, Slay has been the Lions' third cornerback behind Rashean Mathis and Chris Houston.
Houston is questionable with a foot injury. Bill Bentley and Jonte Green figure to get expanded roles if Slay and Houston cannot play.