On 8 December 1997, he was appointed as a director of the Hawthorn Football Club and served in the role for just over eight years before retiring on 29 March 2006. One of the most notable incidents during his term as director was his alleged involvement in the run-up to a bench-clearing brawl between Hawthorn and Essendon in a 2004 encounter that became known as the Line in the Sand Match. During halftime, just before the brawl, Brereton had reportedly told Hawthorn players to "draw a line in the sand" and take a physical stand against Essendon; he denied making that particular remark, but admitted to telling senior players "to stand up to any Essendon aggression".