World heavyweight champion Anthony Joshua and promoter Eddie Hearn are holding Deontay Wilder completely responsible for the breakdown in contract negotiations for a unified title fight. 

Per CBS Sports' Brian Campbell, Hearn explained talks collapsed because Wilder didn't sign a contract after terms were agreed upon:

"No, the reason why we're not getting Wilder is he refused to sign the contract on the terms he agreed. If we didn't want the fight, we wouldn't have ever sent him a contract. I wouldn't have spent four months traveling around and wasting my time with late-night phone calls to agree on terms. We agreed on terms and we sent them a contract, but they didn't send it back, they didn't even send any comments back."

Joshua noted he doesn't like to discuss contract talks publicly, but he "sealed the deal" from his side. 

Wilder's co-manager Shelly Finkel told ESPN's Dan Rafael last month he was "optimistic" the two sides would reach agreement for a fight in the fall. 

Instead, on July 16, Jack Rathborn of the Mirror confirmed Joshua would be defending the WBA Super, IBF, WBO and IBO heavyweight belts against Alexander Povetkin on Sept. 22 at Wembley Stadium. 

Speaking to TMZ Sports after the bout with Povetkin was announced, Joshua said that fight wouldn't impact a potential matchup with Wilder. 

"I'm not focusing on losing, but if I did, that fight is still big because people know what I'm about. They know I'm a worthy challenger," Joshua said. "The athletes make the superfight. Me and Wilder are big punchers, we can both fight."

Given how close both sides appeared to be this time, there's still a chance to eventually make the much-anticipated superfight between the two undefeated heavyweight superstars. It's just going to take longer than boxing fans would have preferred to wait.