Nick Diaz’s hopes for a UFC interim championship rematch have gone up in smoke after the welterweight star flunked a drug test on the weekend of UFC 143.

According to Nevada state athletic commission executive director Keith Kizer, 18 of the 22 fighters from the Feb. 4 event were tested. Seventeen of those tests had no issues, but Diaz tested positive for marijuana metabolites, Kizer wrote in an e-mail sent to several media outlets, including NBCSports.com.

A complaint for disciplinary action has been filed on the commission’s behalf, meaning Diaz faces a possible fine and suspension.

This is the second positive pot test for Diaz, who was suspended six months and fined in February 2007 by the same commission. That violation also cost Diaz a victory, as his rare gogoplata submission win was overturned to a no contest.

"We'll give Nick ample opportunity to provide any defense, if any, that he wants to," Kizer said, the AP reported.

"I am beyond disappointed that he tested positive for marijuana," UFC president Dana White said in an e-mailed statement. "It is now in the hands of the Nevada State Athletic Commission.”

The most recent violation won’t hurt Diaz’s won-loss record because he lost a close but controversial decision to Carlos Condit, but it can potentially cost him hundreds of thousands if not millions of dollars in the near term. Diaz earned a guaranteed $200,000 for his most recent fight, a number that could have gone up substantially based on pay-per-view buys.

A rematch with Condit would have pulled in about the same number, and a potential title fight with Georges St-Pierre down the line probably would have earned him well over $1 million.

Because it’s his second violation, Diaz is subject to a longer suspension, possibly up to one year.

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Despite his loss to Condit, the UFC had quickly warmed up to a rematch in the wake of the bout. While Condit’s camp originally said they would wait to fight fight St-Pierre, who is currently on the mend from knee surgery, Condit himself later reversed course and said he would fight Diaz again.

This is just the latest in a series of issues for the enigmatic Diaz, who once got into a post-event fight at a local hospital. Another time, he took part in a post-fight brawl on CBS, an incident that helped ensure Strikeforce would never again appear on network TV.

Diaz has made no effort to hide his marijuana use in the past. In a past interview with the Los Angeles Times, Diaz detailed how he flushes out his system with herbal cleaners eight days before a test. He has said that he holds a medical marijuana card to combat attention deficit hyperactivity disorder.

Despite that, usage is prohibited under Nevada’s state athletic commission rules, and it will almost certainly cost Diaz a prime portion of his career. Ironically, after his disputed loss to Condit last Saturday, he said he may be “done with this MMA thing.” Most chalked that up to the frustration of the moment, but it seems likely that the 28-year-old is done for the foreseeable future.

Diaz has yet to publicly comment on the positive test.