One of the primary preliminary matches was a standard one-on-one match between Rey Mysterio and Chavo Guerrero. Their storyline first began in July 2006 at The Great American Bash. Guerrero interfered in Mysterio's World Heavyweight Championship match with King Booker by hitting Mysterio with a steel chair, costing him the championship. Guerrero defeated Mysterio the following month at SummerSlam 2006, winning the match after performing a frog splash At No Mercy, Mysterio defeated Guerrero in a Falls Count Anywhere match, pinning him after performing a crossbody off a guard rail. On the October 20 episode of "SmackDown!", Guerrero defeated Mysterio in an "I Quit" match by forcing him to quit after hitting his left knee repeatedly with a steel chair. During the match, Mysterio suffered a real injury—an ACL and patella tendon tear in his left knee. Ten months later, on the August 3 episode of "SmackDown!", a match between Mysterio and Guerrero was booked for SummerSlam.