Atlanta Falcons rookie linebacker Marquis Spruill will miss the season with a left knee injury.

Coach Mike Smith said Thursday Spruill tore his anterior cruciate ligament late in Wednesday's practice. Spruill was on the field for several minutes before walking off with the help of trainers.

The Falcons lost starter Sean Weatherspoon to a season-ending Achilles tendon injury in June.

Spruill, a fifth-round pick from Syracuse, was a third-string linebacker on the team's first preseason depth chart. He was listed behind Joplo Bartu and rookie Prince Shembo.

The depth chart was configured for a nickel defense. He likely would have been a top backup inside linebacker on a depth chart configured for a 3-4 scheme.