Sean O’Malley won’t be fighting at UFC 229 on Saturday due to a potential U.S. Anti-Doping Agency violation, he said today.

O’Malley (10-0 MMA, 2-0 UFC), an undefeated bantamweight prospect who was scheduled to fight Jose Quinonez (7-2 MMA, 4-1 UFC) on the UFC 229 prelims, announced today that he’s been flagged for a potential doping violation and will be unable to compete.

With the UFC and USADA recently changing policy to keep potential failures private until after resolutions are made, O’Malley opted to announce the news himself and explain the situation.

O’Malley said he believes the issue stems from a contaminated supplement and revealed that he’s already working with the necessary people to clear his name of any wrongdoing.

He explained everything in detail on social media (via Instagram):

“Hey guys, Sugar Show here…I want to be the first to let you know about what’s going on. As many of you may have seen, the UFC announced this weekend that they are no longer announcing potential violations of the USADA program, because of the high number of unintentional use cases under the program, and are instead waiting until the end.

“I find myself caught up in one of these exact cases right now. Even though under the new policy, my case would not be public right now, I feel it’s important to be upfront and honest with my fans about why I’m not fighting next weekend.

“I’ve been working with Jeff Novitzky at UFC and I believe that we have already identified a dietary supplement that would have caused this. WE’ve sent remaining samples from the bottle I took to the USADA lab and as well as a full sealed bottle. I’m told that the testing of these supplements can take as long as 30 days.

“I will continue to update you all about the findings, but I fully expect the results will be what I already know, that I did nothing on purpose.

“For everyone that follows me and was excited for my fight I’m truly sorry. It hurts a lot not being able to get out there and do what I love on the biggest stage.

“I have no intention of cheating and am fully confident that the results of this case will show that. I love my fans and I hope the impact on my career is minimal and I’m back to fighting soon.”

UFC 229 takes place at T-Mobile Arena in Las Vegas. The main card airs on pay-pay-view following prelims on FX and UFC Fight Pass.

UFC officials did not immediately reply to MMAjunkie when asked whether a replacement search for O’Malley is underway or if Quinonez will be scratched from the card.

The UFC 229 lineup includes:

MAIN CARD (Pay-per-view, 10 p.m. ET)

• Khabib Nurmagomedov vs. Conor McGregor
• Tony Ferguson vs. Anthony Pettis
• Dominick Reyes vs. Ovince Saint Preux
• Derrick Lewis vs. Alexander Volkov
• Felice Herrig vs. Michelle Waterson

PRELIMINARY CARD (FS1, 8 p.m. ET)

• Jose Quinonez vs. TBA
• Jussier Formiga vs. Sergio Pettis
• Vicente Luque vs. Jalin Turner
• Tonya Evinger vs. Aspen Ladd

PRELIMINARY CARD (UFC Fight Pass, 6:15 p.m. ET)

• Yana Kunitskaya vs. Lina Lansberg
• Scott Holtzman vs. Alan Patrick
• Nik Lentz vs. Gray Maynard
• Ryan LaFlare vs. Tony Martin

For more on UFC 229, check out the UFC Rumors section of the site.