In the spring of 2005, Guerrera had signed a contract with World Wrestling Entertainment (WWE). He debuted on television, wrestling simply as Juventud, on June 18, 2005, defeating Funaki on "SmackDown!"'s sister show "Velocity". On the June 23 episode of "SmackDown", Juventud, Super Crazy and Psicosis (collectively called "The Mexicools") interrupted a match between Chavo Guerrero and Paul London by riding to the ring on a lawn mower and attacking both wrestlers. The following week by week of The Mexicools interrupting matches and beating down seemingly random wrestlers and cutting promos. Juventud quickly established himself as the mouthpiece/leader of the group and began using his old nickname "The Juice".