Olympic gold medal winner and former WBA heavyweight champion Alexander Povetkin has maintained that he did not use banned performance enhancing substances and does not know how steroids entered his body.

On Saturday, Povetkin knocked out France's Johann Duhaupas in six rounds in Russia. Povetkin was originally scheduled to meet Canada's Bermane Stiverne for the interim WBC heavyweight title but Stiverne withdrew after Povetkin's sample, from a December 6th drug test, returned positive for Ostarine, a banned substance. The test result came back only hours before the event was planned to start.

Ostarine is a SARM substance, which athletes use during training. It builds up endurance, like anabolic steroids. The World Anti-Doping Agency (WADA) put SARM substances on its prohibited items list in 2008.

Stiverne himself also tested positive for a banned substance in the weeks leading up to the fight, but a quick investigation revealed that he ingested the substance from an energy drink.

For Povetkin, it was the second time that he tested positive for a banned substance. Back in May, a planned fight with WBC heavyweight champion Deontay Wilder was canceled when Povetkin tested positive for a banned substance a few days before the fight.

Andrei Ryabinsky, the head of the World of Boxing promotion company and Povetkin’s promoter, told RT that the current situation reveals double standards.

“Double standards, no doubt about it. Here’s an example – the investigation over Povetkin and meldonium lasted for nearly six months. It took only several days to settle down Stiverne’s case.

“The key question is why are we getting positive test results? They all repeatedly prove negative in all other laboratories, including the US lab, except for one random sample that we get immediately prior to the fight. Don’t want to jump to conclusions; just want to say it’s a strange coincidence."

Ryabinsky said that Povetkin has been passing doping tests consistently throughout the year, both before and after fights.

“To assert that he has ingested something [prohibited] is simply impossible. Theoretically, I can assume that this substance turned up in his test accidentally. This happens sometimes. At least Stiverne, when he was cleared and allowed to fight, used this phrasing, saying that the [prohibited] substance turned up in his system accidentally,” he said.

Ryabinsky pointed out that, although Povetkin had provided the sample last Tuesday, VADA (Voluntary Anti-Doping Association) chose to notify the fighters of the allegedly failed test only at the last minute, on Saturday.

“This is not normal practice, it’s very strange,” Ryabinsky said. “It’s the second time that right before the fight, all of a sudden, we get a ‘dirty’ test result – one and only, with all others coming clean. This happened before the fight with Wilder, when there had been five tests, and the fourth allegedly turned out to be dirty, while the fifth came out clean again. In the long run, Povetkin was acquitted, but the bout with Wilder was cancelled. Looks like history is repeating itself with Stiverne right now."