Oleksandr Usyk is set to lose his undisputed world heavyweight boxing champion status following a ruling by one of the major boxing organizations.

The 37-year-old initially became the undisputed heavyweight champion by defeating Tyson Fury last May, adding the WBC championship to his existing WBA, WBO, and IBF titles.

However, he will vacate the IBF title as he cannot defend it against the organization's mandatory challenger, Daniel Dubois, given his upcoming obligatory rematch with Fury on December 21 in Riyadh, Saudi Arabia.

The newly-vacant IBF heavyweight championship will now be contested between two British boxers, Anthony Joshua and Daniel Dubois, on September 21 at Wembley Stadium in London, England.

Usyk became the first undisputed heavyweight champion since Lennox Lewis held the distinction for five months from November 1999 to April 2000.

However, Usyk is the first undisputed heavyweight champion since the status became undisputed across all four belts after the WBO was recognized by the other boxing organizations around 2007.

Oleksandr Usyk teases Anthony Joshua and Daniel Dubois

Meanwhile, the Ukrainian seemed at ease with the prospect of losing one of his belts.

Usyk posted a video on the social media platform Instagram, appearing to acknowledge the loss of the belt.

"Anthony and Daniel, listen. I know [the] IBF title [is] important to you. [The IBF belt is] my present to you on September 21," the boxer said.