Just several days after initial reports suggested he'd be headlining the UFC's first-ever event in Russia, former UFC heavyweight champion Fabricio Werdum has landed himself in hot water with the promotion.

This past Monday, MMA Fighting's Ariel Helwani reported that Werdum would be challenging Alexey Oleynik in the main event of UFC Fight Night Moscow this September. On the heels of that report, however, the UFC has just broken some somber news.

Major Setback

It was announced that Werdum failed a United States Anti-Doping Agency (USADA) test, stemming from an out-of-competition sample collected on April 25th. 

Werdum is facing an ant-doping violation, but the substance he tested positive for is not being released, as per policy.

Vai Cavalo's manager, Ali Abdel-Aziz, recently spoke to MMA Fighting on the matter, and revealed that the UFC has yet to inform them if the Oleynik fight is off. He also added that Werdum “did not take anything illegal":

“The entire UFC staff and I are all working together to solve this problem,” Abdel-Aziz said.

“I’m very confident it will be OK. ... It’s a misunderstanding. Something is off. Fabricio did not take anything illegal.”

The Hunt To Recapture Gold

Werdum hasn't been inside the Octagon since suffering a fourth round knockout loss to Alexander Volkov at UFC London this past March. Prior to that, he had won two fights in a row.

The 40-year-old seems dead set on recapturing the UFC heavyweight title he lost to Stipe Miocic several years ago. 

He recently took to Instagram to comment on the news of his anti-doping violation. Here's what he had to say:

"Hey guys, I got up this morning to the news that one of my urine samples from April tested positive for a prohibited substance.

"I am working with my team, the UFC and USADA to understand what happened. I’ve always been careful with everything I take and I’ve always supported a clean sport.

"We will work hard to solve this misunderstanding and I hope soon to be able to go back to the octagon and do what I love"

It should be interesting to see what becomes of Werdum's situation with USADA. Many fighters have claimed that a tainted substance is to blame for the issue, and perhaps we will see the same with Werdum.

Regardless, athletes now knowing exactly what they're putting into their bodies is inexcusable, and USADA will be a reminder of that time and time again.

What are your thoughts on Werdum's anti-doping violation with USADA? Let us know your thoughts on the matter in the comments section below!