Illinois running back Dre Brown says he has torn the ACL in his left knee and will miss a second straight season.
Brown announced on Twitter that he injured it during practice Monday.
Brown said he is not sure if he will be able to play again as he begins what he called "a long process with a lot of question marks."
The injury comes almost exactly a year after he tore his right ACL. He missed his freshman season.
Brown was expected to be a primary backup for sophomore Ke'Shawn Vaughn.
Team spokesman Kent Brown said coach Lovie Smith was not available for comment.
Earlier this month, Illini receiver Mike Dudek suffered his second ACL tear in the span of a year.