Diaz was signed to a two-fight deal with the PRIDE Fighting Championships with the first scheduled to be against Lightweight Champion Takanori Gomi in a non-title fight on February 24 in Las Vegas. PRIDE 33 was Diaz's first fight in the PRIDE organization and at the weight of 160 lb. While Gomi started the fight strongly, once knocking Diaz to the ground, twice ending up in his guard, and opening up cuts around both of Diaz's eyes, the Californian dominated the stand-up battle with his boxing. At the end of the first round, apparently due to poor cardio on Gomi's part, the Japanese fighter was clearly stunned, throwing much wilder punches and barely maintaining his defense. Early in the second round, the fight was stopped to check a cut suffered under Diaz's eye. The second stanza saw a continuation of wild punches by Gomi, then eventually taking the fight to the ground and leaving himself open to a Gogoplata submission by Diaz and tapping at 1:46 of the round. This was the second successful Gogoplata attempt in PRIDE's history (the first performed by future DREAM Lightweight Champion Shinya Aoki on Joachim Hansen less than two months earlier at PRIDE's New Year's event).