LAS VEGAS (AP) -- UFC welterweight Nick Diaz tested positive for marijuana after his loss to Carlos Condit on Saturday night and faces disciplinary action, including a possible suspension and fine, the head of the Nevada Athletic Commission said Thursday. Keith Kizer, the commission's executive director, said Diaz's license was temporarily suspended and he will have 20 days to respond to allegations that a urine sample submitted after the fight tested positive for marijuana metabolites. "We'll give Nick ample opportunity to provide any defense, if any, that he wants to," Kizer said. UFC officials had no immediate comment, though the organization's president, Dana White, said on Twitter on Wednesday that Condit was set to fight Diaz again in a rematch of the co-main event at UFC 143. Condit won the interim welterweight title and a shot at fighting Georges St-Pierre. Diaz was visibly upset at the loss in the close fight and hinted at retirement. "I'm not going to accept this as a loss," Diaz said. "I think I'm done with this MMA stuff, I don't think they can pay me enough to do this again." The marijuana test would be the latest in a string of unpredictable moves from the talented, yet mercurial Diaz outside the ring. Diaz was supposed to fight St-Pierre in September, but the UFC pulled him from the bout for disciplinary reasons after he didn't show up to promotional news conferences in Toronto and Las Vegas without explanation. Condit was Diaz's replacement but the fight never happened because St-Pierre got hurt. White nearly cut Diaz entirely, but instead matched him up against B.J. Penn, a fight Diaz easily won. In 2010, Diaz threw a punch at Jason "Mayhem" Miller that started a brawl in the cage after a CBS-televised Strikeforce event. Kizer said that in April 2007, Diaz lost his license for six months and was fined 3,000 after another positive marijuana test after a submission win over Takanori Gomi in the Pride Fighting Championships.