Welterweight contender Nick Diaz tested positive for marijuana after his interim title bout loss Saturday night to Carlos Condit, Nevada State Athletic Commission executive director Keith Kizer revealed Thursday.
Several fighters who competed on the UFC 143 card were subjected to postfight drug and steroid tests.
"All results received thus far have been negative, except Mr. Diaz [who] tested positive for marijuana metabolites," Kizer said in a statement. "A complaint for disciplinary action against Mr. Diaz has been filed."
UFC president Dana White planned to meet with Condit on Friday in hopes of working out details for a rematch. But that meeting will likely be canceled, now that Diaz faces a possible suspension.
"I am beyond disappointed that [Diaz] tested positive for marijuana," White said. "It is now in the hands of the Nevada State Athletic Commission."
With a rematch against Diaz off the table, White told ESPN.com there is no plan to have Condit put his interim title on the line.
"He will wait [for St. Pierre]," White said.
The failed drug test is Diaz's second in Nevada. He also failed a drug test taken shortly before his win over Takanori Gomi during a Pride lightweight nontitle bout in April 2007.
Diaz was suspended for six months by the NSAC and fined 20 percent of his fight purse. The result of the fight was changed to a no contest.
After losing a unanimous decision Saturday night in Las Vegas to Condit, Diaz promised to retire from mixed martial arts competition.
With a victory, Diaz would have been in line to face current UFC 170-pound titleholder Georges St. Pierre. But with St. Pierre expected to be out of action until November with a torn ACL, there was talk of a rematch with Condit.
But Diaz's manager/trainer Cesar Gracie told ESPN.com Wednesday that the fight would not happen. Gracie would not offer a reason why the rematch would not take place.
Franklin McNeil covers mixed martial arts and boxing for ESPN.com. Follow him on Twitter at www.twitter.com/Franklin_McNeil.