An asteroid and a promise to his mum? Find out five facts about the former heavyweight world champion who's retiring from boxing.
Ukrainian boxer Wladimir Klitschko stands at almost two metres tall and weighs 109 kg. He says that sport was "the best choice of a profession I could have made", but it's time for him to move on. He's ending his career with a record of 64 wins and five defeats.
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In his last fight, the 41-year-old was beaten by current heavyweight world champion Anthony Joshua. Back in 2015, Klitschko was unbeaten for 11 years until a fight against British boxer Tyson Fury that November.
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Wladimir Klitschko followed his brother, Vitali Klitschko, into boxing. Their mum made them promise that they would never fight each other! Don't worry, in this photo they're just practising at a training camp.
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An asteroid a bit like this one was named after the brothers. Asteroid212723 Klitschko was spotted floating through space in 2007 by an observatory in Ukraine, who wanted to thank the brothers for their work with different charities.
Did you know that Wladimir Klitschko has a highest academic university degree and speaks four languages: Ukrainian, Russian, English and German. And although he's waving goodbye to boxing, it sounds like he's going to be pretty busy. He said, "I have achieved everything I dreamed of, and now I want to start my second career after sports".