Oleksandr Usyk's heavyweight journey is officially underway.

The 2018 Fighter of the Year former World cruiserweight king weighed a career heaviest but well proportioned 215 pounds for his official heavyweight debut. Ukraine's Usyk faces Chazz Witherspoon, who looked every bit the part of a late replacement as he checked in at a fleshy 242 pounds, also a career heaviest weight.

The scheduled 12-round non-title fight headlines an 11-fight bill live from a sold-out Wintrust Arena in Chicago, Ill. (Saturday, DAZN, 8:00pm ET/7:00pm local time).

Usyk (16-0, 12KOs) finally enters the heavyweight ranks after a five month delay. The 32-year old southpaw was due to arrive in boxing's glamour division in May, only for a torn biceps injury to cancel his planned showdown versus former title challenger Carlos Takam.

Efforts to reschedule the bout proved just as struggling as finding an alternate opponent for this contest. Event handlers finally settled on unbeaten Tyrone Spong, a former kickboxing star turned rising heavyweight who was pulled from the card after pre-fight random drug testing revealed a banned substance in his system.

Spong and his team continue to appeal the claim, having requested the "B" sample to be tested. In the meantime, the show had to go on which led to the choice of Philadephia's Witherspoon (38-3, 29KOs), a 38-year old former title hopeful and second cousin to former two-time heavyweight titlist Tim Witherspoon who has won eight straight against limited competition.

In the chief support, unbeaten Dmitry Bivol (16-0, 11KOs) makes the sixth defense of his light heavyweight title (excluding interim title fights) as he faces Dominican Republic's Lenin Castillo (20-2-1, 15KOs). Kyrgyzstan's Bivol weighed 174.3 pounds, while Castillo—who has won two straight—came in at 175 pounds.

Highlighting the show's local flavor, reigning unified junior welterweight titlist Jessica 'CasKILLA' McCaskill (7-2, 3KOs) faces Argentina's Erica Farias (26-3, 10KOs) in a rematch to their 10-round thriller in this very venue this time one year ago.

McCaskill—coming off of a Fight of the Year-level title unificaiton win over Anahi Sanchez in May—weighed 138.7 pounds in seeking to repeat her winning effort over Farias, who hit the scales at 138.1 pounds.

FULL WEIGHTS

Oleksandr Usyk 215 lbs. vs. Chazz Witherspoon 242 lbs.—12 rds., heavyweight

Dmitry Bivol 174.3 lbs. vs. Lenin Castillo 175 lbs.—12 rds., light heavyweight

Jessica McCaskill 138.7 lbs. vs. Erica Farias 138.1 lbs.—10 rds., junior welterweight

Movladdin Biyarslanov 137 lbs. vs. Tyrome Jones 136 lbs.—6 rds., junior welterweight

Anthony Sims Jr 168.5 lbs.* vs. Morgan Fitch 167.5 lbs.—10 rds., super middleweight

*Sims Jr. weighed 169 on 1st try, stripped down but was still 0.5 pounds above contracted limit.

Charles Conwell 153.8 lbs. vs. Patrick Day 153.7 lbs.—10 rds., junior middleweight

Joshuah Hernandez 130 lbs. vs. Giovanni Mioletti 130 lbs.—10 rds., junior lightweight

Otha Jones III 129 lbs. vs. Eric Manriquez 130 lbs.—6 rds., junior lightweight

TJ Doheny 124 lbs. vs. Jesus Martinez 124 lbs.—8 rds., 124-pound catchweight

Reshat Mati 151 lbs. vs. Norfleet Stitts 150.5 lbs.—4 rds., junior middleweight

Jenna Johlin Thompson 147 lbs. vs. Summer Lynn 147 lbs.—4 rds., welterweight

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox