Although he cast doubt on his ability to pass a drug test prior to the biggest fight of his life, Nick Diaz is in the clear following UFC 158.

The Regie des alcools des courses et des jeux (Quebec’s athletic commission) today passed along word that drug tests for the March 16 pay-per-view event came back clean.

A total of six competitors were tested, QAC rep Joyce Tremblay wrote in an email to MMAjunkie.com (www.mmajunkie.com). The substances tested for are confidential, she added, and the individuals tested were not named. The commission did not answer a follow-up email requesting an explanation for why the names weren’t released.

In UFC 158’s headliner, welterweight champ Georges St-Pierre dominated Diaz over five rounds to retain his title. Afterward, Diaz contemplated retirement, then asked for a rematch.

Reps close to him now say he is retired unless he gets a rematch with St-Pierre or a superfight with Anderson Silva.

Beforehand, Diaz, who previously has been suspended twice for marijuana, put the UFC on notice that a third fail was possible.

“I’m sorry if I don’t pass the test, but I think it should work out,” he said. “I’ve passed plenty of them before, unless they just weren’t testing me. I wonder how much they test people around here.”

UFC President Dana White said he would probably cut Diaz with a positive test.

In the co-main event, Johny Hendricks outpointed Carlos Condit despite a late-fight rally from the former interim welterweight champ.

For complete coverage of UFC 158, stay tuned to the UFC Events section of the site.

(Pictured: Nick Diaz)