Ashburn, Virginia - With little over a month to go before the regular season kicks off, Washington Commanders head coach Ron Rivera has made a shock change to his coaching staff.

The Commanders are parting with defensive line coach Sam Mills III over what head coach Ron Rivera on Tuesday called a "difference of philosophy."

Assistant defensive line coach Jeff Zgonina, who played one season with Mills' father in the NFL, has been promoted to lead coach of the defensive line.

"He (Mills) is a friend and always will be a friend," Zgonina said of Mills. "I've known him almost his whole life – I played with his dad. But I have a job to do and he had a job to do and we just have to keep moving forward."

Rivera, who also has a long-standing relationship with the Mills family, revealed this history made his decision "very difficult." The two have been working together since 2011, when they joined the Carolina Panthers.

"I've known Sam a long time, and (he's) a very good football coach," the former Chicago Bears player said. "And I really appreciate everything that he's done. He helped us win the division the first year, and things got tough last year. There were some things I felt I wanted to change."

Mills' father, Sam Mills, was posthumously inducted into the NFL Pro Football Hall of Fame this past weekend.

The Commanders are currently practicing on their training camp in Ashburn, Virginia.