Usyk KOs Dubois in controversial title bout, sets sights on Fury

Usyk knocked out Dubois in the 9th round to retain his heavyweight titles.
Dubois' team disputed a low blow call in the 5th round that allowed Usyk time to recover.
Usyk expressed interest in fighting WBC champion Tyson Fury next.
The matchup would determine the undisputed heavyweight champion.
Longer delays could jeopardize the chance for all four belts being on the line.