MNM was called up to WWE's SmackDown! roster in April 2005, with Matthews undergoing a name change to "Joey Mercury". They made their debut during Carlito's interview segment "Carlito's Cabana", where they interrupted an interview between Carlito and Rey Mysterio, and attacked Mysterio. This provoked a feud between MNM and Mysterio and his partner, Eddie Guerrero, over the WWE Tag Team Championship. Two weeks later, in their debut match on the SmackDown! brand, they defeated Mysterio and Guerrero to win the WWE Tag Team Championship after Guerrero refused to tag into the match. While Nitro and Mercury held the championship, Melina was placed in an angle with Heidenreich. She publicly mocked him and was the impetus for an attack on him by Nitro and Mercury. In July, MNM were scheduled to face Heidenreich in a two-on-one handicap match, but attacked him before the match started. Road Warrior Animal saved Heidenreich from the attack and as a result, Heidenreich and Road Warrior Animal challenged Mercury and Nitro for the WWE Tag Team Championship at The Great American Bash. MNM lost the match and the championship to Heidenreich and Animal at The Great American Bash.