Oleksandr Usyk is no longer boxing’s undisputed heavyweight champion.

The Ukrainian, 37, defeated Tyson Fury last month to add the WBC heavyweight title to the array of world championships he already held, becoming the first undisputed champion of the four-belt era. However, this accolade lasted less than two months after he confirmed on social media that he was stepping away from the IBF title after being unable to face mandatory challenger Daniel Dubois.

Usyk will next fight in a contractually-guaranteed rematch with Fury later this year. Dubois has been promoted to the reigning IBF champion and is expected to defend his crown against Anthony Joshua in September.

“Anthony and Daniel, listen. I know the IBF title is important to you. It is my present to you on September 21,” Usyk said on social media.

Dubois, whom Usyk defeated last August, scored an eighth-round finish of the previously unbeaten Filip Hrgovic in Saudi Arabia earlier this month.

The development means that the Usyk-Fury rematch, which is expected to take place in December, will not have the same undisputed stakes as their initial bout in May.