On the October 18 episode of "Nitro", Mysterio and Konnan teamed up together to defeat Harlem Heat for the World Tag Team Championship. Mysterio, however, was injured during the match and was sidelined as a result. Billy Kidman substituted for Mysterio and teamed with Konnan during their title defense against Harlem Heat and The First Family, in which the Filthy Animals went on to lose the title back to Harlem Heat. Mysterio returned in early 2000 and remained a steady performer, eventually joining the New Blood faction in early 2000 opposing the Millionaire's Club. On the August 14 episode of "Nitro", Mysterio and Juventud defeated The Great Muta and Vampiro to win the World Tag Team Championship. They were stripped of the title after Ernest Miller pinned Disco Inferno with the stipulation that if he pinned Disco, Mysterio and Guerrera would be stripped of the title. The Filthy Animals then feuded with The Natural Born Thrillers in the fall of the year. At Fall Brawl, the Filthy Animals fought the Thrillers to a no contest in an Elimination tag team match. Mysterio reformed his tag team with Kidman and the two challenged for the World Tag Team Championship in a Triangle match at Halloween Havoc, facing the champions Natural Born Thrillers and The Boogie Knights, where the Thrillers retained.