year with a victory over future PRIDE Lightweight Champion Takanori Gomi to earn his first MMA championship, the Rumble on the Rock Lightweight Championship, in K-1 Fighting Network's Rumble on the Rock, an MMA organization promoted by Penn's brother, and Fighting and Entertainment Group (FEG), the parent company of the largest kickboxing organization, K-1. Penn received his first UFC Championship in 2004 at UFC 46. Penn jumped up in weight classes to challenge the five-time defending UFC Welterweight Champion Matt Hughes to fill a title contention slot in a division where Hughes had already defeated all the available opposition. Heavily favored to win, Hughes lost the fight four minutes into the first round by rear naked choke after giving up his back with only 23 seconds left in the round, in a bout which remains as one of the biggest upsets, as well as one of the greatest submission victories in mixed martial arts history. Fighting and Entertainment Group Penn signed to fight for the Japanese Fighting and Entertainment Group's (FEG) K-1 promotion citing a lack of challenging fights left for him in the UFC. The UFC promptly stripped him of the welterweight title, claiming Penn breached his contract and that the signing constituted as him refusing to defend his title. Penn filed a suit against the UFC and publicized his side of the conflict, claiming his UFC contract had already expired. Penn filed a motion to stop the UFC from awarding a new welterweight title, but that motion was denied. In his second fight for FEG, Penn fought again at welterweight and defeated Duane Ludwig at the 2004 K-1 MMA Romanex show in under five minutes by arm triangle choke. Following the Ludwig fight, Penn moved up in weight class to face the undefeated Rodrigo Gracie at middleweight. Penn won by decision, extending his winning streak to four fights. On March 26, 2005, at the inaugural event of FEG's new MMA promotion Hero's, Penn faced future UFC Light Heavyweight Champion Lyoto Machida, losing by unanimous decision at K-1 Hero's 1. The fight happened at an open weight class with Penn weighing in at and Machida weighing in at . Later that year at K-1 World Grand Prix Hawaii, Penn returned to middleweight to face Pride Fighting Championship veteran Renzo Gracie, which he won by unanimous decision. Return to the UFC In early 2006 at UFC 56, UFC president Dana