The Challenge: Rivals is the 21st season of the MTV reality game show, The Challenge. Rivals takes place in Costa Rica, Argentina, and Patagonia. The season used former cast members from The Real World and The Challenge. Rivals marked the first season of The Challenge not to include any cast members from Road Rules. The season featured a format in which players were teamed with their arch enemies from past seasons of The Real World and The Challenge. The season premiered on June 22, 2011, and concluded with the "S#!% They Should Have Shown" special on September 7, 2011. This is the first edition of the Rivals series, with Rivals II and Rivals III following in 2013 and 2016, respectively. Contestants Teams Format This season of The Challenge featured a brand new format, consisting of 14 same-gender teams — seven male and seven female. Each team will consist of players who will be paired with their "worst enemies," whom they have engaged in bitter feuds, fights and rivalries with in previous Real World and/or Challenge seasons. This format was inspired by ESPN columnist Bill Simmons in a mailbag by someone known as "B.J. from Brooklyn (where it was dubbed “Mortal Enemies” but maintained the premise) Simmons and Dave Jacoby further discussed this idea on the B.S. Report, Simmons' podcast. Each team participates in numerous challenges (sometimes called "missions"), which are followed by an elimination round called "The Jungle." Each challenge is alternatively designated as either a male or a female challenge day. The winning team of the gender not designated for the Jungle is awarded $2,000. The winning team whose gender is designated for elimination wins immunity from the Jungle, while the team that finishes last is automatically sent to the Jungle. An open deliberation and vote then held among the players to determine which team of the same gender will face the last-place finisher in the Jungle. The team who wins the elimination round returns to the game and has a shot at a $300,000 prize, while the losing team is eliminated from the game. At the end of the season, six teams will compete in the final challenge — three of each gender. The first-place male and female teams win $100,000 apiece, second-place wins $50,000 and the third-place finishers go home empty-handed. Pre-season rivalry backgrounds Rivals combines individuals who have had acrimonious or at least strained relations or