Former boxing champions Wladimir Klitschko and Vitali Klitschko are preparing for the fight of their lives, as the former enlisted in the Ukrainian reserve army three weeks prior to Thursday’s Russian invasion and the other brother—the mayor of Kyiv, Ukraine—said this week he’d also take up arms.

“I’m calling to all international partners to observe this tragedy that is happening nowadays in Ukraine,” Wladimir said. “I just want to tell you we must stay united against this aggression, against Russian aggression. Don’t let it continue happening in Ukraine. Don’t let it happen in Europe and eventually the world. United we’re strong. Support Ukraine.”

Also Thursday, Vitali said he was ready to fight in what’s “already a bloody war,” and added, “I don’t have another choice” but to take up arms against Russian invaders.

Russia invaded Ukraine early Thursday in what President Vladimir Putin said was a “special military operation.” Putin said he intended to “demilitarize” the country, as opposed to occupying it.

Two hours after Vitali’s announcement, his brother chimed in with a tweet: “The world is watching how reckless and deadly imperialism is, not just for #Ukraine but the whole world. Let history be a lesson to not be repeated.”

Former world heavyweight champion Wladimir Klitschko announced his retirement from boxing on Thursday after a 21-year career that culminated in a loss to Anthony Joshua in April.

Boxer Wladimir Klitscko Retirement

The 41-year-old Ukrainian Klitschko made the announcement on his YouTube channel early Thursday morning, and also shared the video on Twitter:

The announcement came amid rumors of a rematch between him and England’s 27-year-old Joshua. That bout — held before a sold-out crowd of 90,000 at London’s Wembley Stadium on April 29 — marked Klitschko’s 29th heavyweight title fight appearance. Klitschko went down three times overall in the bout and was stopped in the 11th round, thus failing to defend his title.

That was Klitschko’s second straight defeat after a huge upset loss to Tyson Fury 17 months prior that cost him the unified world championship he had held for nearly ten years.

Klitschko (64-5, 54 KOs) had the right to an immediate rematch against Joshua, whose promoter Eddie Hearn of Matchroom Boxing had begun coordinating with the Ukrainian’s team to set up another fight. Both camps had set a Nov. 11 date for a rematch in Las Vegas, but Klitschko backed out at the last minute.

“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. “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.”

Hearn admitted he was disappointed there will not be a rematch but paid tribute to Klitschko, per MailOnline’s Riath Al-Samarrai:

“We are obviously disappointed from an event perspective because the rematch was huge, but from a personal perspective I am happy for Wladimir,” said Hearn, who learned of Klitschko’s retirement from the Ukrainian’s manager, Bernd Boente on Thursday. “He has had a tremendous career and leaves with a great legacy, in great health and with everything he needs in life. He could have made millions for this fight, but he already has millions.”

Klitschko first rose to fame in Germany, where he fought in sold-out soccer stadiums across the nation. However, he also spends much time in the United Sates, where he and his longtime fiancée — actress Hayden Panettiere — are raising a toddler daughter. The 6-foo-6, 240-pound Ukrainian is one of the most decorated boxers in history: he won the Olympic super heavyweight gold medal as an amateur in 1996, and was a two-time world champion as a professional.

“Especially after this terrific fight at Wembley Stadium it was a very tough decision for Wladimir to make,” Boente said. “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. 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.”

Klitschko’s second reign as world heavyweight champion lasted 9 years, 7 months and 7 days (from April 2006 to Nov. 2015), the second-longest heavyweight title tenure in history behind only legend Joe Louis, who held the title for 11 years, 8 months and 8 days. Klitschko’s reign ended with his loss to Fury. During the reign, Klitschko made 18 consecutive defenses, third-most in division history behind only two other legends, Louis (25, the all-time record for any weight class) and Larry Holmes (20).

“Twenty-seven years ago [as an amateur] I started my journey in sports and it was the best choice of a professional I could have ever made,” Klitschko said.

“Because of this choice, I’ve travelled the world, learned new languages, created businesses, built intellectual properties, helped people in need, became a scientist, entrepreneur, motivator, hotelier, trainer, investor and much else. I was and am still capable of doing all this because of the global appeal of the sport of boxing.

“At some point in our lives we need to, or just want to, switch our careers and get ourselves ready for the next chapter and chart are new course toward fresh challenges. Obviously, I’m not an exception to this and now is my turn. I’m honestly doing this with the greatest respect for the new challenges, but also with tremendous excitement, passion, dedication expecting and hoping that my next career, which I’ve already been planning and working on for some years, will be at least as successful as my previous one. “Finally, instead of just saying thanks and goodbye, I want you to continue to enjoy me in this new and exciting journey. When we’re together we’re more creative, more efficient, more productive and simply stronger in every way. Together we’re the driving force.”

LONDON, ENGLAND – APRIL 29: Anthony Joshua (White Shorts) and Wladimir Klitschko (Gray Shorts) in action during the IBF, WBA and IBO Heavyweight World Title bout at Wembley Stadium on April 29, 2017 in London, England. (Photo by Richard Heathcote/Getty Images)

There will be no rematch for boxing’s World Heavyweight title, at least not on July 9.

Citing a “severely sprained ankle,” heavyweight world champion Tyson Fury (25-0, 18 KOs) has withdrawn from his scheduled rematch with former title-holder Wladimir Klitschko (64-4, 54 KOs).

“About 10 days ago I went over on my ankle, sprained my ankle,” Fury said in a video released on his Instagram account Friday. “I’ve been to the hospital and had X-rays and MRI scans and all that stuff. They say it’s not broken but it’s badly sprained. … So the fight will be postponed.”

The tension between these pair of giants has been far from gentle.

Fury has been roasted by critics after his insensitive comments regarding homosexuals and the (in)equality between the genders.

Klitschko shot back after Fury stuck both feet in his mouth.

“I’m fighting a guy who can’t hold his mouth on certain things,” Klitschko said at a recent media day. “I was in shock at his statement about women, the gay community, and when he got to the Jewish people he sounded like Hitler. The man is an imbecile,” Klitschko said of Fury. “He’s an imbecile champion.”

HIGHLIGHTS FROM FURY VS. KLITSCHKO I

Fury also drew criticism recently after rubbing his pot-like stomach, taunting Klitschko, asking him how it would feel to be beaten by a man with a beer belly.

Some have speculated that Fury’s shape, or lack thereof in regards to boxing, is the real reason behind the postponement.

Coincidentally, the two men have been forced to postpone a fight with each other due to injury before.

Klitschko had the first fight pushed back from October to November 2015 after sustaining a calf injury in training. Fury responded to the news of that postponement by calling Klitschko a “b—-,” and later tweeted that he would be getting drink to celebrate, with a photo of five pints of Guinness and the hashtag “f—Klitschko.”

It is unclear when the fight will be rescheduled, but Fury intimated his medical team told him to suspend training for a couple of months.

“Keep off it for 6-7 weeks,” Fury said of his doctor’s advice. “I tried to still train a bit. I had a second opinion a week later and I got the same advice.”

Klitschko took the news in stride.

Although he expressed disappointment, the former 9-year title-holder remained confident he can recapture the WBO, WBA and IBF World Title belts.

“Of course, I am currently disappointed about the cancellation. As well as for my fans, I’m very sorry, they were all very excited for this rematch,” Klitschko said in a statement. “But one thing is also clear: This just means I’ll get my title belt a few weeks later.”

At a news conference in Manchester on Wednesday, British boxer Tyson Fury removed his T-shirt, turned to Ukrainian opponent Wladimir Klitschko and pointed to his flabby belly, taunting: “Shame on you, you let a fat man beat you.”

Tyson Fury Teases Wladimir Klitschko Ahead Of World Heavyweight Rematch

This was just one of the many wild moments of the expletive-laden and at-time shocking news conference at the Manchester Arena between two fighters competing to become the next world heavyweight champion on July 9.

Fury, 27, began his teasing of Klitschko by waltzing into the room backed by music and cheerleaders, and then by dancing himself. The 40-year-old Ukrainian simply sat motionless for most of the extravaganza, occasionally shaking his head at something he heard.

Klitschko’s nine-year reign as world heavyweight champion came to an end at the hands of Fury in a unanimous decision in Germany in November.

Fury has become known for being very outspoken and even controversial in his views on certain issues. He has previously criticized abortion, openly disagrees with homosexuality, and has made sexist comments like “a woman’s best place is in the kitchen and on her back.” He also said doping should be officially allowed in all sports to make it “fully fair.”

“I’m not OK with what comes out of Fury’s mouth, his statements,” Klitschko said Wednesday. “For example, that all homosexual men and women and paedophiles belong in the same place, in jail basically. So that is basically where he sees Elton John and the Queen.”

Klitschko also added that he wants to win the rematch “not just for myself but for the people … and the better reputation of the heavyweight champion.”

Fury, however, does not seem ready or willing to change. Despite holding one of the most prestigious titles in boxing and in all sports, he continues to offend many people with his insensitive remarks.

Fury has won all 25 of his professional fights, 18 by knockout.

“You got beaten fair and square the first time in Germany on your own turf in front of all your own people – you got whooped,” Fury said. “You’ll need to be about 1,000 times better because you landed about four shots in 12 rounds.”

Klitschko said that although he felt he was in perfect physical shape for his last fight against Fury, he was “mentally absent.”

Less than two weeks after claiming the IBF’s World Heavyweight Championship, Tyson Fury has been stripped of the title.

The British boxer lost the belt due to his refusal to grant certified challenger Vyacheslav Glazkov a shot at the title. Instead, Fury chose to face Wladimir Klitschko in a rematch.

Lindsey Tucker, championships chairman at the IBF, told BBC Sport: “It’s true he’s been stripped of his IBF belt. Our challenger was Glazkov, but instead Fury’s gone and signed a rematch clause with Klitschko.”

Fury has recently been under fire for comments he made about women and gays. He said that “a woman’s best place is in the kitchen and on her back” and that acceptance of homosexuality is a sign of the apocalypse.

Fury has denied the latter through social media.

PHOTO: Tyson Fury (green shorts) on his way to victory over Christian Hammer in a Heavyweight Contest by singing ‘Elvis’ at the O2 Arena on February 28, 2015 in London, England. (Photo by Richard Heathcote/Getty Images)