Oleksandr Usyk will make his long awaited heavyweight debut on Saturday against Chazz Witherspoon in a scheduled 12-round fight at the Wintrust Arena in Chicago.
Promoter Eddie Hearn announced on Tuesday that Matchroom Boxing settled for Witherspoon after initial opponent Tyrone Spong was disqualified for failing a drug test on Monday.
Former MMA fighter from Suriname Spong, was removed from the bout for testing positive in two urine samples collected by the Voluntary Anti-Doping Association, with one of the substances reported to be clomiphene.
Clomiphene is usually taken as post cycle therapy to moderate testosterone levels now that its no longer being synthetically injected.
38-year old Philadelphia native Witherspoon (38-3 29 KOs), who has only two fights under his belt since 2016, agreed to take take the bout barely one week to the fight date.
Usyk, Olympic gold medalist for Ukraine in 2012 was first designated to face Carlos Takam on May 25 at the MGM National Harbor in Oxon Hill, Maryland, but a torn right biceps scuppered that fight.
The 32-year old Southpaw unified the cruiserweight divisio, becoming the first man to do so, following his unanimous decision win against Murat Gassiev in the final of the World Boxing Super Series in July 2018.
Four months later, he successfully defended all four belts with an eighth-round knockout of Tony Bellew and sending the Liverpool fighter into retirement, before giving up the titles and announcing he would move up to the heavyweight division.
A victory for Usyk this weekend will see him challenge the winner of the December 7 rematch between unified heavyweight world titleholder Andy Ruiz Jr. and Anthony Joshua.