World heavyweight champion Oleksandr Usyk has been ordered by the WBO to begin negotiations with Joseph Parker for a mandatory title defence.
Parker, 33, retained his interim WBO title in February with a second-round knockout win against Martin Bakole.
Ukrainian Usyk is the WBC, WBA (Super) and WBO heavyweight champion thanks to his second successive victory against Tyson Fury in December.
Usyk, 38, and Parker have 30 days to find an agreement or the WBO will order purse bid proceedings.
Britain’s Daniel Dubois, who holds the IBF heavyweight belt, is already in talks to face Usyk for the undisputed heavyweight title.
Dubois was set to face Parker on 22 February but withdrew because of illness and is not looking to reschedule that fight.
New Zealand’s Parker held the WBO title between 2016 and 2018, beating Andy Ruiz Jr to claim the vacant belt before losing it to Anthony Joshua following two successful defences.
After suffering the third defeat of his career against Joe Joyce in 2022, Parker has won six in succession, including a victory against former WBC champion Deontay Wilder.
Usyk is yet to lose in 23 fights as a professional, winning 14 by knockout.
Saudi Arabia has hosted most of the big heavyweight bouts in recent years, with Usyk’s two most recent contests against Fury taking place in Riyadh.
Usyk was undisputed champion at cruiserweight before stepping up to heavyweight and achieving the same feat.
However, the Olympic gold medallist vacated his IBF title following his first win over Fury in 2024, which meant interim champion Dubois was upgraded to full champion before his victory over Joshua in September.