Michigan State not only lost to Notre Dame on Saturday, but the nation's No. 1 defense lost part-time starter Jairus Jones to a knee injury.
Jones, a linebacker, sprained an MCL early in the first quarter of Saturday's 17-13 loss to the Fighting Irish, multiple outlets reported. He is expected to miss the next six weeks.
"Jairus has been playing very, very well and has done an outstanding job for us," Michigan State coach Mark Dantonio said.
Jones, a senior, is a converted safety who switched to linebacker in the spring. He has two interceptions this year.
The Spartans' defense allows 188.8 yards per game.