The Crusierweight Champion , Chavo Guerrero was the final entrant and pinned Mysterio to win with the assistance of his father Chavo Guerrero , Sr. , thus keeping the WWE Cruiserweight Championship . The Cruiserweight Champion , Chavo Guerrero , was the final entrant and pinned Mysterio with a reversal of Mysterio 's Sunset Flip to win with the assistance of his father Chavo Guerrero , Sr. , thus retaining the title .