At the UFC 158 pre-fight press conference, Nick Diaz made a veiled reference to UFC champion Georges St-Pierre being on steroids.
"The strong guy on steroids would like to ignore it," said Diaz. "And he wants to get the takedown and win the round."
After further talk, an incredulous GSP lost his cool.
"You really think I'm scared of you?" blurted out St-Pierre. "You are crazy in the head. We'll see Saturday night if I'm scared of you... I didn't say anything bad. I'm not on steroids."
Diaz repeated the remarks, more pointedly, during a radio interview before the fight.
"I believe that he's on plenty of steroids," said Diaz. "And I don't think they test around here either and I doubt I'll be tested here as well. I don't care what they're saying or marketing to the media, I don't think either of us are going to be tested and if so, he's probably got a bottle of piss in his pocket. I doubt they're standing over him making sure he's not on steroids."
St-Pierre of course has never tested positive for PEDs. At one point BJ Penn make reference to GSP and PEDs, but later apologized.
At the post-fight press conference, GSP definitively refuted the PED charge
“Never took steroids in my life,” said St-Pierre. “I’m for Olympic testing in my sport. I’m up to do the test for the Olympic test. I have no problem with that.
“I’m not a cheater – never cheated in my sport. And I think TRT - I’m against TRT. I’m against all this. If you want my opinion, you can test me any time, no problem. I’m for the testing. I think it should be more regulated.
“For someone to say to me I’m athletic, I take that as a compliment. For him, in his mind to say, ‘He needs to be on steroids, he’s very athletic’ – for me, it boosts my confidence by saying that.”
St-Pierre's reference to "Olympic style" testing is to testing done at unscheduled points throughout the year, rather than during fight week, as is generally the case currently in mixed martial arts.