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 to not include any cast members from cancelled series Road Rules. The season featured an incendiary 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