After both camps failed to negotiate terms, reigning WBA (Regular) world champion Kubrat Pulev's proposed matchup with mandatory challenger Michael Hunter is headed for purse bids later this month.

The WBA have today officially called a purse bid, scheduled for May 27 in Houston, Texas, and it will be conducted by WBA Championships Committee Vice-Chairman Julio Thyme.

With a 75%-25% split in the champion's favour, Bulgarian veteran Pulev (32-3, 14 KOs) will be obligated to make his first defence against the division's top available contender after No. 1-ranked contender Fabio Wardley's request to face Jarrell Miller on June 7 was approved.

Miller withdrew citing a shoulder injury and has other issues to contend with as the heavy-handed American seeks a return to prominence after going winless in his last two high-profile bouts against Daniel Dubois and Andy Ruiz Jr.

Australia's unbeaten heavyweight prospect Justis Huni (12-0, 7 KOs) has stepped into the breach on short-notice after elbow surgery earlier this year, and Tuesday they had a launch press conference before their Portman Road stadium fight in three weeks' time.

Hunter (24-1-2, 17 KOs), by contrast, is unbeaten in 14 fights since a wide, 12-round unanimous decision defeat by Oleksandr Usyk for WBO world cruiserweight honours in April 2017.

Victories over Martin Bakole and Sergey Kuzmin have aged well for the 36-year-old, while his agemate has largely stagnated and now has a promotional dispute to contend with.

Pulev, who outpointed Mahmoud Charr in December, turned 44 earlier this month.

Hunter (24-1-2, 17 KOs), was tabbed to return April 19 and promised to produce a statement against compatriot Christopher Lovejoy (20-1-1, 20 KOs) before the fight fell through, with "contractual differences" involving promoter Don King cited. Instead, circumstances outside his control may have swung the odds in his favour.