River v Boca - inside the world's fiercest rivalry / The vicious rivalries tearing apart Pete Hegseth's Pentagon / Hoops legend backs Clark as media, fans talk racial dynamics, rivalry and athletic achievement / USA-Canada 4 Nations Face-Off championship racks up historic viewership as tense rivalry continues / Why USA vs. Canada matters, and how the rivalry has already triggered a rich new era in international hockey / 'No bigger rivalry': USA, Canada to renew history / NFL Rivalries: What is the oldest rivalry in history? / College basketball rankings: Purdue, Indiana on opposite trajectories ahead of rivalry showdown / Letters to Sports: UCLA-USC rivalry smack talk goes both ways / Follow live: Historic rivals collide as Steelers host Cowboys