Both boxers are undefeated but not invulnerable.
Fury, who is the WBC and lineal champion, struggled in October in a non-title fight against Francis Ngannou, the former UFC heavyweight champion who was making his pro boxing debut. Fury escaped with a controversial victory by split decision.
Usyk, who owns the other heavyweight belts, was knocked down by Daniel Dubois in his last fight. He rallied to win that bout in August by knockout.
The matchup, originally set for February, was delayed by three months when Fury suffered a deep cut over his right eye in training.
Now the wait is over. The crown of undisputed heavyweight champion waits to be claimed.
Follow along for updates and highlights throughout the day, including the main event between Tyson Fury and Oleksandr Usyk.