Later on, Guerrera became an announcer on "Thunder" in order to remain on-screen while rehabilitating an injury. On November 29, 1999, Guerrera defeated Jushin Thunder Liger to win the IWGP Junior Heavyweight Championship on "Nitro." The next week, he would lose the title back to Liger, as Psicosis substituted for Guerrera due to injury (in reality, Guerrera and Jerry Flynn were arrested for DUI, thus no-showed). After his injury healed, he joined former rival Rey Mysterio Jr., Konnan, Billy Kidman, and others to form The Filthy Animals. During the group's run, Guerrera and Mysterio Jr. became the World Tag Team Champions.