Joseph Parker tested positive during a doping test conducted the very day of his 11th-round loss to British heavyweight Ipswich-born Wardley.
Fabio Wardley along with the New Zealander were part of a pulsating bout held in London on 25 October to decide the next next in line for the WBO against undisputed world heavyweight champion Ukrainian champion Usyk.
The fighter had positioned himself as next in line to meet Oleksandr Usyk subsequent to putting together an impressive six-fight winning streak, but placed his shot at the title on the line in London and endured an 11th-round stoppage.
A standard screening administered to Parker by the Voluntary Anti-Doping Agency on the day of the bout showed an adverse result which leaves the 36-year-old in a difficult position to demonstrate his cleanliness.
The boxer's representatives released an announcement which read: "The anti-doping body alerted all relevant parties that Joseph Parker returned an adverse finding after a drug screening administered on the fight day. As the investigation continues, no additional comment are forthcoming currently."
The New Zealand boxer became heavyweight champion six years ago before he lost the WBO title through a points decision versus Anthony Joshua at the Millennium Stadium in 2018.
Parker has been a frequent visitor on British soil from that point, fighting eight times in total in Britain and transferring to the Irish capital for fight camps alongside highly regarded trainer Andy Lee over the past few years.
Under the tutelage of Lee, Parker recovered from his 2022 loss to Joe Joyce to achieve several successes positioning him front of the queue to challenge Usyk until he lost to the British fighter.
Following Parker's sample showed a failed test when he fought Wardley, allegedly for cocaine, an inquiry about the test outcome has commenced.
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