Oklahoma State's Jim Knowles will join Ohio State as a defensive coordinator on Ryan Day's staff, per ESPN's Adam Rittenberg.

Knowles will replace Kerry Coombs and become Day's third defensive coordinator in three seasons.

"What is most important at this time is that we put our players in the best position possible to finish the season with a win in the Rose Bowl," Day told reporters. "To that end, we will continue our planning and preparation for the game with our current staff of 10 assistant coaches."

Knowles has served as Oklahoma State's defensive coordinator for the past four seasons and was a 2021 finalist for the Broyles Award, which is given to college football's top assistant coach.