The New Zealand heavyweight tested positive as part of a doping test administered the very day of his 11th-round stoppage to UK boxer Ipswich-born Wardley.
Wardley together with the New Zealander participated in an intense contest held in London on 25 October to establish who would become mandatory WBO contender to undisputed world heavyweight champion Oleksandr Usyk.
Joseph Parker was previously the leading contender to meet the champion after compiling a notable six-fight winning streak, however put his mandatory challenger status in jeopardy in London and endured a stoppage in round eleven.
A routine test conducted on Parker by Vada the day he fought showed an adverse result which leaves Parker facing a challenge to clear his name.
The boxer's representatives published a statement which read: "The anti-doping body notified everyone involved regarding Joseph Parker tested positive subsequent to a doping test carried out on October 25th. As the investigation continues, no additional comment are forthcoming for now."
Joseph Parker was crowned titleholder six years ago prior to he lost the WBO title by unanimous decision to British star Joshua in Cardiff 24 months later.
The fighter remained a regular competitor on British soil after that, fighting eight times altogether in the UK and moving to Ireland for preparation with highly regarded trainer Andy Lee during this period.
Under the tutelage of Lee, Joseph Parker recovered from his 2022 loss versus British heavyweight Joyce to secure a string of victories positioning him front of the queue to challenge the champion before he suffered defeat to the British fighter.
Subsequent to the boxer produced a positive test during the Wardley bout, allegedly for cocaine, a probe regarding the results has commenced.
A passionate historian and travel writer with expertise in Mediterranean archaeology and Sicilian culture.