Alabama outside linebacker Terrell Lewis underwent successful surgery for a torn ACL on Tuesday, according to a statement from coach Nick Saban.

The statement adds that Lewis, a rising junior, sustained the injury while training last week and that the timetable for his return is currently unknown.

The former four-star defensive end missed 10 games last season with an upper arm injury he suffered in the season opener against Florida State. He returned for the Iron Bowl and made his first career start in the national championship game against Georgia, in which he had a crucial sack in overtime.

During his freshman season, Lewis totaled 11 tackles in 11 games.

Before his injury, Lewis was expected to share first-team snaps off the edge with Anfernee Jennings and Christian Miller in 2018. However, with recovery and rehab for most ACL tears landing between roughly 6-9 months, Lewis could miss a significant portion of the season.