The biggest heavyweight fight in boxing – maybe the biggest fight in the sport, period – is certainly a showdown for the undisputed championship between British countrymen Tyson Fury and Anthony Joshua.

Some have speculated that perhaps the fight could take place at the end of the year, but that is unlikely for a variety of reasons.

Most have focused on the fact that even though former titleholder Deontay Wilder exercised his contractual right to a third fight with Fury following a seventh-round knockout loss in their rematch on Feb. 22 in Las Vegas, he might be open to accepting a step-aside deal to forgo an immediate third fight with Fury.

Wilder, however, who is recovering from surgery on his left biceps following the loss, has said time and again that he will face Fury next, although the bout likely would not happen until at least November.

But even if Wilder was willing to make a deal to step aside to allow Fury to pursue a fight with Joshua – Fury co-promoter Frank Warren has denied rumors that Wilder was offered a deal to step aside -- the path would still not be clear. The reason is because Joshua has a signed agreement to make a mandatory defense in his next bout against Kubrat Pulev, who is focused on that being his next fight.

“We have signed contracts for that fight and everything is ready,” Pulev told BoxingScene. “We worked on this contract for maybe two months and it was not so easy. But now we have this contract and I am ready. I don’t want to wait. I want the title fight with Anthony Joshua and I will beat him really good and get the second knockout against him. I am the mandatory challenger and these are the rules. It doesn’t matter who wants to box him or who he wants to box. Anthony Joshua has to box me.”

Joshua (23-1, 21 KOs) and Pulev (28-1, 14 KOs), of Bulgaria, were scheduled to fight on June 20 at the 70,000-seat Tottenham Hotspur Stadium in London but it had to be postponed due to the coronavirus pandemic.

The fight is due to be the first defense of Joshua’s second title reign. He lost his unified belts by shocking seventh-round knockout to Andy Ruiz Jr. in June at New York’s Madison Square Garden in what was Joshua’s United States debut before regaining the belts via one-sided unanimous decision in an immediate rematch in December in Diriyah, Saudi Arabia.

Joshua promoter Eddie Hearn of Matchroom Boxing and Pulev co-promoters John Wirt and Ivaylo Gotzev of Epic Sports and Top Rank’s Bob Arum have been talking about efforts to reschedule the fight, not about any sort of step-aside deal.

“The fact is we have a signed and sealed contract with Joshua, so there are no arguments there,” Gotzev told BoxingScene. “There are two separate signed contracts between four fighters – a signed contract for Fury and Wilder to have a third fight and Wilder has executed his rights. That’s a known fact. And there is also the contract we have for Anthony Joshua to fight Kubrat Pulev. We’ve waited for this fight for a long time. We’re not going away. We must fight Joshua next, per our signed agreement.

“There hasn’t been a single word about a step-aside deal. We haven’t been approached about one. We are all interested in rescheduling Joshua-Pulev as soon as possible.”

Gotzev said earlier this week he was on a teleconference with Hearn, others from Matchroom Boxing, Arum and others from Top Rank, to discuss rescheduling the bout.

“We all talked about the current conditions and the progression of the coronavirus,” Gotzev said. “We’ve given ourselves time to explore different possibilities.”

One potential date is July 25 but whether the fight can still be staged in London remains to be seen because of the coronavirus situation. It also remains to be seen if the fight can be held with spectators, regardless of where the bout takes place.

“One possibility might include finding a different venue than the Tottenham Stadium if necessary,” Gotzev said. “We do understand some countries are experiencing tougher times because of this virus and the U.K. is one of them. So it will come down to their regulations if we can have the fight there or if we have to have it with no crowd or if we have to go somewhere else.”

The British Boxing Board of Control, which regulates professional boxing in the United Kingdom, announced this week that it believes the sport could resume there in July but with no spectators, a maximum of five bouts per show and testing for Covid-19.

Doing a heavyweight world title fight with no spectators is not ideal, but Gotzev and Hearn have both said it may have to be the case.

“Just because there might not be a crowd, rest assured it will be an exciting fight for the people watching on TV,” Gotzev said. “We are looking at options about where to have the fight and we have some spectacular venues we are looking at. No one expected this, so it’s nobody’s fault if we have to move the fight, but all parties agree we will work through it and make the fight happen sooner than later.”

Pulev said he couldn’t care less where the fight takes place.

“I am ready to fight everywhere,” Pulev said. “It doesn’t matter if it’s London or anywhere else. Anthony Joshua said the fight had to be in London and I said, ‘OK, no problem.’”

But what if a deal to step aside was offered to Pulev?

“I am ready for this fight against Joshua, so I don’t know. Nobody knows. I want this fight,” said Pulev, who has won eight fights in a row since losing by knockout to then-unified world champion Wladimir Klitschko in November 2014. “When somebody comes to me and tells me something and offers me something, maybe. I don’t know, but I want this fight, I am ready for this fight and I believe this fight will happen this year.

“I’ve waited a long time for this fight with Anthony Joshua. I am the longtime mandatory for this fight, but I am open for talking, no problem. But I want this fight. That’s it.”

Dan Rafael was ESPN.com's senior boxing writer for fifteen years, and covered the sport for five years at USA Today. He was the 2013 BWAA Nat Fleischer Award winner for excellence in boxing journalism.