Daniel Dubois is on a three-fight knockout streak since he last fought Oleksandr Usyk, so what's changed for the 27-year-old as he bids to become undisputed heavyweight champion?

Regardless of what happens in his rematch with IBF heavyweight champion Daniel Dubois on Saturday, WBA, WBC and WBO champion Oleksandr Usyk already has a Hall of Fame resume. Beating Dubois would make Usyk -- a former undisputed cruiserweight champion -- undisputed heavyweight champion for the second time in his career.

Oleksandr Usyk has denied claims that his age could be the decisive factor in Saturday's undisputed world heavyweight title clash with Daniel Dubois. Reigning WBA, WBO and WBC champion Usyk, 38, is more than 10 years older than IBF belt holder Dubois.