Wladimir Klitschko has announced his shock retirement from boxing with immediate effect, ending any chance of a rematch against heavyweight world champion Anthony Joshua.

The 41-year-old Klitschko, who enjoyed a 21-year career in the win in which he won 64 of his 69 fights, was famously beaten by Joshua in an almighty heavyweight scrap on 29 April this year in an 11th round stoppage.

The Ukrainian retires as one of the sport's true greats, having held the WBA, IBF, WBO and IBO heavyweight titles, as well as the lineal crown, and remains the second-longest serving heavyweight champion of all time behind Joe Louis with 18 consecutive defences over a nine-year span.

Who next for Anthony Joshua? Show all 8 1 /8 Who next for Anthony Joshua? Who next for Anthony Joshua? Joshua defeated Carlos Takam - so who's next? Getty Who next for Anthony Joshua? Deontay Wilder A fight between Joshua and America's WBC heavyweight champion Wilder, 31, would likely prove the richest in the heavyweight division. The combination of two charismatic, explosive punchers would appeal both in the UK and the US, but may have such commercial potential that they would choose to delay until next summer. Getty Who next for Anthony Joshua? Joseph Parker New Zealand's WBO champion Parker carries less threat and appeal than Wilder but also represents less of a risk. The 25-year-old controversially beat Tyson Fury's cousin Hughie in September, and is one of only two fighters against which a unification match-up could be made. Getty Who next for Anthony Joshua? Hughie Fury Hughie Fury is looking to bounce back from the defeat to Parker and a domestic fight with Joshua could be on the cards as a build-up fight to Wilder. His schedule would fit with the time Joshua would want to fight next. Getty Who next for Anthony Joshua? Tyson Fury Fury is arguably Joshua's biggest rival but he first needs to get his licence back, lose about six stone and start training regularly again. Until then this will just be a dream fight but seeing his cousin box Joshua could be the inspiration Fury needs to get fit again. Getty Who next for Anthony Joshua? Tony Bellew The former WBC cruiserweight champion's unexpected defeat of David Haye has given him far more appeal in the heavyweight division than any would have predicted. He has that rematch with Haye to deal with first and if he gets past that then a fight with Joshua could happen. However, he seems incapable of providing Joshua with much of a test, but the money involved in fighting the champion will become such that any potential offers will be tempting. A match-up between the two is also straightforward to make, given they are both promoted by Matchroom. Getty Who next for Anthony Joshua? David Haye Haye used to hold the heavyweight world title until he lost to Wlaimir Klitschko and subsequently retired in 2011, only to launch a comeback that has never really taken off. He suffered a ruptured Achilles tendon in his defeat by Tony Bellew earlier this year, and while he is now preparing to avenge that loss, he could yet be a future opponent for Joshua and desperately wants him after Bellew. Getty Who next for Anthony Joshua? Dillian Whyte Whyte fought on the undercard in Cardiff and there is genuine dislike between him and Joshua. Joshua actually wanted him to replace Pulev following the fighter's withdrawal. They have already fought once but Whyte wants another shot while Joshua would love to bury his fellow Brit's career. Getty

Joshua declared on Wednesday that he wanted Klitschko to agree to a rematch by the end of the month in order for a November bout to take place in Las Vegas, with promoter Eddie Hearn already starting talks over a second fight in the space of the year between the two giants.

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However, Klitschko released a statement on Thursday morning to declare his immediate retirement, thus ending any chance of a rematch against the 27-year-old Briton.

"I deliberately took a few weeks to make my decision, to make sure I had enough distance from the fight at Wembley Stadium,” Klitschko said in a statement released on his website. “As an amateur and a professional boxer, I have achieved everything I dreamed of, and now I want to start my second career after sports.

"I would have never imagined that I would have such a long and incredibly successful boxing career. I'm very thankful for this. Thanks to everyone who has always supported me. Especially my family, my team and my many fans."

Klitschko’s manager, Bernd Boente, added: "Especially after this terrific fight at Wembley Stadium it was a very tough decision for Wladimir to make. But he has always emphasized that he wanted to retire if he didn’t have enough motivation anymore. Therefore this is definitively the right decision.

Klitschko was expected to trigger the rematch clause in his contract and face Joshua again (Getty)

"Wladimir accomplished everything in his unique boxing career. He dominated the Heavyweight division for over a decade. He fought in sold-out arenas and stadiums worldwide and millions of fans around the world watched his fights on TV. It has been a privilege for me to accompany Wladimir on this unique journey."

Hearn immediately took to Twitter to confirm he was made aware about the decision earlier today, and wished his best to the Ukrainian.

"I heard the news this morning from Bernd Boente that Wladimir Klitschko has decided to retire from boxing," said Hearn. "We wish him all the success."

Joshua will now begin talks to fight Kubrat Pulev (Getty)

Hearn immediately took to Twitter to confirm he was made aware about the decision earlier today, and wished his best to the Ukrainian.

"I heard the news this morning from [Klitschko's promoter] Bernd Boente that Wladimir Klitschko has decided to retire from boxing," said Hearn. "We wish him all the success."