Canelo Alvarez’s reign as undisputed super-middleweight champion is on the brink of ending, with International Boxing Federation (IBF) rules separating the sport’s most popular fighter from one of his four 168-pound belts.

According to multiple boxing sources who spoke to BoxingScene Tuesday, Alvarez (61-2-2, 39 KOs) intends to relinquish his IBF belt rather than participate in an ordered June 6 purse bid at IBF offices in New Jersey for a fight against that sanctioning body’s mandatory contender, little-known William Scull of Cuba (22-0, 9 KOs).

The IBF is confident in its position that Alvarez, 33, is now due to confront their mandatory challenger next.

Alvarez has stood as undisputed 168-pound champion since November 6, 2021, when he stopped then-IBF champion Caleb Plant in the 11th round.

The four sanctioning bodies take turns presenting their mandatory to the undisputed king, and Alvarez has successfully defended his position a record four times, most recently claiming a unanimous-decision triumph over Mexican countryman Munguia May 4 in Las Vegas.

While WBA President Gilberto Mendoza has claimed his mandatory contender, Brooklyn’s Edgar Berlanga, is next in line, IBF President Daryl Peoples was set Monday to clarify the matter and assert his position with Mendoza.

Alvarez’s manager and trainer, Eddy Reynoso, did not immediately return messages left him by BoxingScene Tuesday.

By refusing to participate in the ordered June 6 purse bid for a bout against Scull, Alvarez vacates the title.

That turn of events leaves Scull, 31, who fought on the pre-pay-per-view portion of the Alvarez-Munguia card, to look elsewhere for a title-fight opponent and IBF rules stipulate it will be against the organization’s No. 2 contender, Russia’s Vladimir Shishkin (16-0, 10 KOs).

Shishkin’s promoter, Dmitriy Salita, said a negotiating period will occur for the promoters to settle on a venue and date for the bout.

Salita said he’d prefer the bout be streamed by his broadcast partner DAZN, and said it’d even be “possible” for the fight to be on the same card as Alvarez-Berlanga if that fight materializes for Sept. 14.

Scull’s promoter, however, wants Scull-Shishkin to be in Germany.

“It’s my dream … it’s easy work,” Shishkin told BoxingScene Tuesday of the title fight and how he’ll fare against Scull. “(Scull’s) nothing special. I think I can knock him out sometime after the sixth round, no problem.”

Boxing officials, including a promoter and matchmaker who attended an event in Copenhagen this past weekend, said the expectation is that Scull-Shishkin will be negotiated in June.

“The interest of (Scull promoter) Agon Sports is to bring the fight to Germany,” where Scull fought eight consecutive times before his Las Vegas bout, said an official familiar with the Copenhagen discussions who spoke on the condition of anonymity because he is not authorized to speak publicly on the talks. “I would expect the fight to take place in August or September, after the Olympics.”

Salita said he requires assurances the judges will be “fair and neutral.”

“To me, it’s very special to have been with Vladimir since his (2019) arrival in the U.S. (at Detroit’s Kronk Gym under trainer “SugarHill” Steward), starting on “ShoBox” and getting here,” Salita said. “I believe this could lead Vladimir to the Canelo sweepstakes.”

The IBF, following a 2000 bribery trial of former president Robert Lee, has been a stickler for enforcing mandatory positions, and Alvarez’s situation is only the latest example.

When reminded that involvement in an Alvarez fight ensures far greater riches in 3% sanctioning fees than a Scull-Shishkin fight in Germany, an IBF official told BoxingScene, “It is what it is.”

And even the Scull camp understands why Alvarez would surrender his belt as the possible bouts against Berlanga in New York or unbeaten double-undisputed Terence Crawford or unbeaten former super-middleweight champion David Benavidez in Saudi Arabia loom.

“Fighting Scull? He’s not known in the states or anywhere really,” the boxing official said. “It doesn’t make sense.”