Notre Dame will be without two starting linemen on Saturday.
Coach Brian Kelly told reporters Thursday that right guard Christian Lombard will miss the rest of the season after undergoing back surgery to repair a herniated disc, and nose guard Louis Nix III will not travel with the Irish (5-2) to play Air Force (1-6) after missing practice this week because of knee tendinitis.
Lombard, a 6-foot-5, 315-pound senior, shifted to guard after starting at right tackle last season. Kelly said Steve Elmer, a 6-5, 317-pound freshman, will replace Lombard.
Nix injured his shoulder in last Saturday's 14-10 victory against USC, but it is his knee that will keep the 6-2, 357-pound senior on the sideline this weekend.
Kelly said on Tuesday that the team would be "careful" with Nix during practice this week as the Irish prepared to face Air Force's option-heavy offense that relies on cut blocks.
Kona Schwenke will replace Nix in the starting lineup. Schwenke, a 6-3, 303-pound senior, started three of the four games at defensive end as Sheldon Day tried to return from a sprained ankle.
Kelly also said backup defensive end Jarron Jones was in Rochester, N.Y., on Thursday because of a death in the family. Jones is expected to join the team in Colorado Springs, Colo., and will be available Saturday.