Anthony Joshua's Aug. 12 rematch with Dillian Whyte in London is off after the Voluntary Anti-Doping Association informed Matchroom Boxing that Whyte "returned adverse analytical findings as part of a random anti-doping protocol," the promoter announced on Saturday.
Eddie Hearn's Matchroom Boxing is attempting to secure a replacement opponent for Joshua on one week's notice, sources told ESPN.
Whyte said he was "shocked and devastated" to learn of the test's findings, while proclaiming his innocence in a social media post on Saturday.
"I can confirm without a shadow of a doubt that I have not taken the reported substance, in this camp or at any point in my life," Whyte's post read. "I am completely innocent and ask to be given the time to go through the process of proving this without anybody jumping to conclusions or trial by media.
"This is not the first time that I have been reported as having an adverse finding for a substance which I have not taken, and as I did last time, I will again prove that I am completely innocent" Whyte wrote referring to a June 2019 failed test which he was later cleared of by UK AntiDoping after his victory over Oscar Rivas a month later.
Joshua, the former two-time unified heavyweight champion, was set to fight Whyte in a return bout nearly eight years later. When they met in December 2015, Joshua defeated Whyte via seventh-round TKO but was forced to survive some rocky moments early on against his fellow Englishman.
Olympic bronze medalist Filip Hrgovic, who is set to fight Demsey McKean on the undercard, is the most attractive replacement option for Joshua. Another possibility is British gatekeeper Derek Chisora, who is slated to fight Gerald Washington on the undercard.
Joshua (25-3, 22 KOs) scored a wide-points victory over Jermaine Franklin in his first fight with Derrick James, ESPN's 2022 Trainer of the Year, leading his corner. The victory came five months after Whyte scored a controversial decision victory over Franklin.
Now training in Dallas, Joshua, 33, is looking to become a three-time heavyweight champion.
An Olympic gold medalist, Joshua lost his three titles to Andy Ruiz in June 2019 in one of the biggest upsets in heavyweight championship history.
Joshua, ESPN's No. 4 heavyweight, parted ways with longtime trainer Rob McCracken following the first Usyk loss and then ended his partnership with Robert Garcia after only one fight.
This is the third time Whyte has found himself embroiled in a controversy surrounding accusations of performance-enhancing-drug use. Following a victory in October 2012, it was found Whyte tested positive for a banned stimulant. He subsequently received a two-year ban.
Whyte returned to in-ring competition in November 2014. He went on to establish himself as bona fide heavyweight contender with quality wins over Chisora and former champion Joseph Parker.
Whyte (29-3, 19 KOs) was stopped in Round 6 by Tyson Fury in his long-awaited first title shot last April at London's Wembley Stadium. Prior to the Fury loss, Whyte, a 36-year-old Londoner, scored a fourth-round TKO of Alexander Povetkin in March 2021 to avenge a fifth-round KO defeat in August 2020.
Whyte is ESPN's No. 7 heavyweight.