Kelly said Schmidt, a redshirt junior, will have surgery on Tuesday.
Schmidt suffered the injury in the third quarter of the No. 8 Fighting Irish's 49-39 win over Navy on Saturday, which pushed its record to 7-1 on the season. Schmidt, a bit undersized at 6 feet and 235 pounds, has been one of the Irish's biggest surprises in a defense that ranks 28th in the nation. He led the team in tackles and added two forced fumbles and two interceptions.
"Everybody is going to have to pick up the slack for a guy that did most of the work," Kelly said, according to The Chicago Tribune. "He's a big loss."
According to the Tribune, freshman Nyles Morgan will likely have the first chance at replacing Schmidt in the starting lineup.