Nicholas Robert Diaz (born August 2, 1983) is an American professional mixed martial arts fighter . He is the current Strikeforce Welterweight Champion and a former WEC and IFC Welterweight champion . He has also competed in the Ultimate Fighting Championship, Pride Fighting Championships, and Elite Xtreme Combat before it ceased operations . Diaz was promoted to black belt in Brazilian Jiu-Jitsu by Cesar Gracie on May 8, 2007 . After years of practicing various combats sports and martial arts, Diaz became a professional mixed martial arts fighter in 2001 just after his 18th birthday and won his first fight, submitting Mike Wick with a triangle choke at IFC Warriors Challenge 15 . Diaz would become a champion in just his second professional fight, decisioning Chris Lytle for the IFC United States Welterweight title in July 2002 at IFC Warriors Challenge 17 . The two came into the fight with a good amount of bad blood between them . They reportedly exchanged heated e-mails before and after the official signing of the fight, which was spurred on by Diaz's public opinion that Sanchez and the rest of The Ultimate Fighter participants were being given an easier path to the top compared to the rest of the fighters in the UFC . Things went to another level in the locker room before the fight when Diaz taunted Sanchez and threw a shoe at him . Diaz was obviously confident coming into the bout but was unable to achieve success in the match, ultimately losing to Sanchez by unanimous decision. Diaz complained of a "greasy substance" on Diego's arms that impeded Diaz's takedowns. While no illegal lubricant was ever investigated, Sanchez's hair was considerably wet-looking throughout the fight, suggesting that his hair product may have leaked onto his shoulders. During the televised post-fight interview in the ring, Diaz continued the controversy by declaring that he respected Sanchez fighting ability but did not think he deserved to be there, despite Sanchez's win. .