Former world heavyweight champion Joseph Parker has denied taking a banned substance after being notified that he returned an adverse result in an anti-doping test conducted on the day of his shock defeat to Fabio Wardley.

The 33-year-old New Zealander said on social media that he was “surprised” to learn of the result, which came from a Voluntary Anti-Doping Association (VADA) test carried out on October 25.

Parker was stopped in the 11th round by British contender Wardley, a loss that cost him his position as the WBO mandatory challenger to undisputed heavyweight champion Oleksandr Usyk.

In a statement issued on Saturday, promoters Queensberry confirmed the news:

“The Voluntary Anti-Doping Association (VADA) last night informed all required parties that Joseph Parker returned an adverse finding following an anti-doping test conducted on 25 October in relation to his bout with Fabio Wardley. While the matter is investigated further, no additional comment will be made at this time.”

Parker insisted he has never used performance-enhancing drugs and expects to be cleared once the investigation is complete.

“Before my recent fight, I took a voluntary test and have now been informed that it returned an adverse result,” Parker posted on Instagram. “This came as a real surprise to me. I did not take any prohibited substance, I do not use performance-enhancing drugs and do not support their use. I am co-operating fully with the process now underway and I am confident the investigation will clear my name.”

UK tabloid The Sun reported that Parker tested positive for cocaine.

The setback comes after Parker had revived his heavyweight ambitions with six consecutive victories, including high-profile wins over Deontay Wilder, Zhilei Zhang and Martin Bakole, seemingly putting him back in contention for a shot at Usyk.

Depending on the results of the ongoing investigation, Parker could face a suspension.

Parker first became world champion in 2016, holding the WBO title until a unanimous decision defeat to Britain’s Anthony Joshua in Cardiff in 2018.