Eddie Hearn, promoter for IBF, IBO, WBA, WBO heavyweight champion Anthony Joshua (21-0, 20 KOs), explains that the unification with WBC champion Deontay Wilder (40-0, 39 KOs) is going to be pushed back - because of the recent agreement between middleweights Gennady Golovkin and Canelo Alvarez.

A few days ago, Golovkin and Canelo reached a deal to fight for a second time on September 15 at the T-Mobile Arena in Las Vegas.

Hearn's offer to Wilder was for a fight in September - and obviously that can't happen now.

Hearn explains that Wilder and his handlers took too long to accept the terms - with the biggest sticking point being the location - with Joshua having the home advantage of a UK venue.

If the Wilder fight happens, it would have to take place in October or November - or even in February of next year. It all depends on the dates lining up for both Sky Sports and Showtime - and the available venue dates.

"We made an improved offer [to Wilder's team] about four weeks ago," Hearn told iFL TV. "On Monday they emailed us saying they accept the terms, now we want to see a contract. We wanted to do the event in September. Our original offer was based on a September fight

"Obviously Canelo-Golovkin was announced and it's only 10 or 11 weeks to September 15. Because of how long they've taken to come back, September's out. It doesn't work for US TV. It doesn't work in a build-up sense either.

"We're looking now -- if we do Wilder -- for more like October, November. Josh wants to do this fight at Wembley, we all do. But we can't do the fight in Wembley if it's not in September. Now we're looking at Cardiff. Now we've got to go back to them, go through the dates etc.

Hearn does caution that if Wilder and his handlers take too long to sign the actual contract - then Joshua will move forward with a fall fight against WBA mandatory challenger Alexander Povetkin - and then face Wilder in the first quarter of 2019.

"The Wilder fight is 100 percent happening," Hearn said. "The max you're going to have to wait is seven or eight months. But hopefully you might have to wait three or four months. I'm almost certain this gets signed.

"We are under pressure time wise so I'm hoping they come back in good time on the contract because if they are going to mess around, and it's not going to get done, we'll jump in and fight Povetkin in September. We can sign for Wilder now for December or for February, no problem. But I'm not going to wait until July or August and still not have a fight scheduled."