Sports information director Kent Brown on Friday confirmed Svetina's injury. Svetina broke his foot Tuesday during practice.
The junior started 11 games in 2013 and was fifth on the team in tackles with 57. He entered preseason practice as a likely backup but one who could see a lot of playing time.
Brown said sophomore B.J. Bello and "a host of others" will move into Svetina's slot.
Backup running back Donovonn Young is also out after suffering a concussion this week. Brown said the timetable for Young's return isn't clear.
The Illini open the season at home Aug. 30 against Youngstown State.