Griffin made his UFC debut at "UFC 63" against David Lee. He won the bout via rear-naked choke submission in the first round, and later used the prize money to move to Las Vegas and joined the Xtreme Couture camp. Former teammate Nick Diaz criticized Griffin as a "gym jumper", but Griffin rejected the accusation. He began 2007 with a fight against Frank Edgar at "UFC 67". The back-and-forth bout ended with Edgar trapped in a tight kneebar, but the judges unanimously scored the bout in his favor, handing Griffin his first professional loss. He rebounded with two decision victories over Clay Guida and Thiago Tavares at "UFC 72" and "UFC 76", respectively. All three of his bouts in 2007 were judged in the top 10 best of year.