Chazz Witherspoon 38-3 (29) has stepped in as a late replacement to face former undisputed cruiserweight champion Oleksandr Usyk 16-0 (12) at the Wintrust Arena in Chicago on Saturday night.
Ukrainian southpaw Usyk, 32, was scheduled to make his long-awaited heavyweight debut against Tyrone Spong 14-0 (13) before the 34-year-old failed a drugs test.
Witherspoon is undefeated in the past five years and is coming off a second-round stoppage of Santander Silgado in Atlantic City in March.
“I can’t wait to face Usyk in Chicago,” said Witherspoon. “I have been in training ready for a big fight, and it doesn’t get bigger than this. Oleksandr is stepping up to heavyweight – and he’s going to find out that it’s a totally different game.
“I’ve won my last eight fights and I really feel that I’ve been waiting in the wings for a huge opportunity like this and I am going to put every ounce of myself into the fight on this massive stage.”
Earlier this week promoter Eddie Hearn took to social media to advise fight fans of Spong’s failed drugs test.
“We have been contacted by VADA to inform us that there has been an adverse finding in Tyrone Spong’s test,” Hearn wrote.
“It has been sent to the State of Illinois Commission and further information will be released in the morning. We have reserve opponents standing by.”
Spong reportedly tested positive for the banned substance clomiphene.