Matchroom boss Eddie Hearn has admitted defeat in his attempts to secure a rematch for Anthony Joshua against Wladimir Klitschko.
Hearn broke the news on Thursday that former unified king Klitschko has decided to hang up his gloves with immediate effect.
"I heard the news this morning from Bernd Boente that Wladimir Klitschko has decided to retire from boxing. We wish him all the success," said Hearn.
This news opens the door for a potential Las Vegas unification between Joshua and WBC champion Deontay Wilder, most likely on November 11.
Joshua is due for a mandatory with Kubrat Pulev in the immediate future, although an unification with the American would appeal more to US TV backers at Showtime.
'AJ' has already visited Las Vegas to sound out the T-Mobile Arena for a possible November bout with Wilder, who would also need to delay a fight with his number one challenger and ex-opponent Bermane Stiverne.
All that's left to open serious negotiations is to ask the IBF and WBC for special dispenation for a massive four-belt battle, with the winner then going on to defend against both Pulev and Stiverne in 2018.
Regarding Klitschko, the giant Ukrainian leaves the sport with a standout 64-5 and a reign at the top which will be hard to match in the future.
'Dr. Steelhammer' is a two-time, five-belt top division ruler and in his last spell held the crown for almost a decade until suffering a shock loss to Tyson Fury in 2015.