COLUMBUS, Ohio –– Ohio State co-defensive coordinator Greg Mattison will retire at the end of the month, following two seasons with the Buckeyes and almost 50 years in coaching altogether.

Head coach Ryan Day made the announcement Friday morning, and said the team will begin working on finding a replacement for the Madison, Wisconsin, native.

"He will not be an easy guy to replace," Day said.

Mattison joined the Buckeye coaching staff in January 2019 ahead of Day's first season as head coach, a move that followed eight years at Michigan as defensive coordinator and then defensive line coach.

Before his run at Michigan from 2011-18, Mattison had worked as either the defensive coordinator or defensive line coach for the Wolverines from 1992-96.

"His career speaks for itself," Day said. "What he's done and accomplished on the field, but more importantly, it's what he's done off the field. The relationship and respect he has around the country as one of the best coaches and the impact he's had on so many people."

In 2019, Mattison ran the Buckeye defense along Jeff Hafley, but following Hafley's move to Boston College, Kerry Coombs was named Ohio State's defensive coordinator. Mattison remained the co-defensive coordinator for the 2020 season.

Mattison was the head coach at Riverdale and Logan High School in Wisconsin from 1971-75 before spending most of the next 45 years coaching either at the collegiate or professional level.

Aside from Ohio State and Michigan, Mattison coached at Illinois, Cornell, Northwestern, Navy, Notre Dame and Florida, among other programs.

In the NFL, Mattison was a linebackers coach and then defensive coordinator for the Baltimore Ravens from 2008-10.

"Can't thank him enough for what he's done. I know he's gonna really miss it, but he's gonna have an opportunity to spend some time with his grandkids and his children after an unbelievable career in coaching football," Day said.