Wladimir and Vitali Klitschko have doubled down on their pledges to defend their country from foreign invaders, and have promised to keep Ukraine free or die trying.
The two former boxing world champions are currently in Kyiv, where they have taken up arms against the Russian and Belarusian forces which began their assault on the country last Thursday.
Vitali Klitschko feels a special need to lead by example as the mayor of his city.
"I am very proud to see how patriotic people are," he told CNN . "We're not interested in how strong the Russian army is, we're ready to fight.
"And we're ready to die for our home country and for our families, because it's our home. It's our future and somebody wants to come to our home and steal our future from us."
He went on to say he believes that he and his fellow fighters can hold off Vladimir Putin's invaders for "such a long time" if they can stay alive.
The elder of the Klitschko brothers went on to speak of his pride that so many of his compatriots have risked their lived and stayed to fight for their country's freedom, despite many having no military experience.
"We stayed in front of one of the strongest armies in the world," he added. "The will to be independent is the main priority for us. And we're defending our families, our city, our country and our future.
"There is a huge patriotic movement right now. Old people, can you imagine? Doctors, actors, actors from the theatre, many professions that never had no expectation to fight, to keep weapons.
"But right now they are coming to us, they're ready to fight. It's amazing."
The Klitschko brothers are not the only boxing icons to take up arms in the Ukrainian capital.
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Current world heavyweight champion Oleksandr Usyk has flown back to his homeland, and is currently protecting an underground bunker in Kyiv where civilians are taking shelter.
Usyk joined the Kyiv Territorial Defence force and has pledged to kill Russian invaders if necessary.
"If they will want to take my life, or the lives of my close ones, I will have to do it," he said when asked if he would be willing to take someone's life.
"But I don't want that. I don't want to shoot, I don't want to kill anybody, but if they will be killing me, I will have no choice.
"Maybe, it'll sound sentimental but my soul belongs to the Lord and my body and my honour belong to my country, to my family.
"So there is no fear, absolutely no fear. There's just bafflement. How could this be in the 21st century?"
