It was a first for boxing, with all four heavyweight belts on the line. The gripping magnitude of the event made it the most meaningful heavyweight fight in a generation.

And it was won dramatically, with Ukraine’s Oleksandr Usyk rallying through the second half and capturing victory by split-decision when the final scorecard revealed he won it by one point.

In celebration, Usyk lifted up a special belt with one word: UNDISPUTED.

“A great night of boxing and a great fight worthy of the hype,” International Boxing Federation President Daryl Peoples said.

But now, with word coming Tuesday that former champion Tyson Fury intends to exercise his rematch clause, which will likely lead to an October 12 rematch in Saudi Arabia, the IBF is poised to take its belt away from Usyk.

The IBF’s mandatory title contender, Croatia’s Filip Hrgovic (17-0, 14 KOs), has waited his turn three times, according to a spokesman for Team Hrgovic, and he’s not willing to wait any longer as Hrgovic prepares for his June 1 bout against England’s Daniel Dubois (20-2, 19 KOs) at Kingdom Arena in Saudi Arabia.

“It’s time,” the spokesman said.

Peoples explains IBF rules make it “pretty clear” that Hrgovic is entitled to his title fight.

“The rule is, you cannot have a clause in your contract that guarantees you a return bout (rematch) that will interfere with your mandatory,” Peoples said. “It’s not a secret among promoters. Everyone, more or less, knows the consequences of having those clauses. We’ve been down this road before.”

Before committing to such a clause, promoters, managers and fighters obviously weigh the impact of losing the belt versus the purse money that can be earned for a rematch of this magnitude.

In acknowledging that’s likely true in the case of Usyk-Fury, Peoples said something more.

“As far as the IBF rules go, any reigning champion is going to be able to ask for an exception,” Peoples revealed. “Any reigning champion can ask for an exception to any IBF rule.”

He was asked: Usyk can ask the IBF to sanction the rematch and keep it an undisputed affair again?

“They have the right to,” Peoples said.

Why hasn’t he?

“I don’t know,” Peoples answered.

So is Hrgovic-Dubois going to be an IBF title fight, for certain?

“I don’t know,” Peoples said. “Right now, Hrgovic-Dubois is not for any title. At this point. I’m sure there’s people making decisions behind the scenes before they approach me about anything.”

That’s certainly true.

BoxingScene reached out to Usyk manager Egis Klimas, who said it’s still premature to know how Usyk and those in Saudi Arabia, particularly His Excellency Turki Alalshikh, will proceed.

“We will speak with people in Saudi to see their plans and, of course, (ask) what (Usyk) wants to do,” Klimas said.

The Hrgovic spokesman wondered what “the point” of retaining the undisputed banner on the rematch was. “They fought for undisputed already. At some point, it’s enough. (Hrgovic) has been mandatory for two years, pretty much.”

True, but he’s never beaten an active champion, and Dubois is not one, having lost to Usyk by ninth-round knockout nine months ago.

So while Team Usyk is now free to request an IBF exception, it also must confront its current contractual agreement with Team Hrgovic to let him proceed toward a title fight if Usyk is not fighting him now.

The IBF cannot order or stipulate any financial figure required for another step-aside fee asking Hrgovic to wait again and keep the undisputed mantra in place.

That has to be haggled out by the Usyk and Hrgovic representatives. Or it doesn’t, and Usyk can just relinquish the IBF belt.

A similar situation occurred in November when the IBF stripped its welterweight belt from undisputed champion Terence Crawford and gave the belt to Jaron “Boots” Ennis.

“If (Team Usyk) asks for an exception, it goes to the (IBF) board of directors, and if the board grants it, then special conditions will likely be applied,” said Peoples, such as ensuring Hrgovic fights the winner.

“These are all managerial and promotion decisions,” Peoples said.

In other words, boxing business as usual.

At least for one night, it was all on the line and all settled in the ring by the two fighters.