Nickolas Robert Diaz (born August 2, 1983) is an American professional mixed martial artist who competes in the middleweight division of the Ultimate Fighting Championship (UFC). Diaz is a former Strikeforce, WEC and IFC welterweight champion and a UFC title challenger. He also notably competed in PRIDE, EliteXC, DREAM, and Shooto. Nick is the older brother of fellow UFC fighter Nate Diaz, with the pair of brothers being one of the biggest influences in the sport of MMA.