Grace broke the fibula in his right leg in a 37-34 win over Arizona State. Irish coach Brian Kelly said Grace will remain in the Dallas area for a few days after having a rod inserted into his leg Sunday morning. Estimated recovery time is 4-6 months.
Grace, the Fighting Irish's starting middle linebacker, is tied for the team lead with 40 total tackles. The redshirt sophomore entered the year as the successor to Manti Te'o, last season's Heisman Trophy runner-up.
Grace is the third defensive contributor the Irish have lost since opening preseason camp in August, as starting drop linebacker Danny Spond was forced to retire because of hemiplegic migraines and defensive line regular Tony Springmann suffered a season-ending knee injury.
Fifth-year seniors Dan Fox and Carlo Calabrese often platooned with Grace among the two inside linebacker spots and figure to start alongside each other there. Kelly said redshirt junior Kendall Moore, former walk-on Joe Schmidt and freshman Michael Deeb could see extended time now as well.
Kelly also said that receiver Daniel Smith fractured his left ankle and will have surgery once the swelling goes down.