Oleksandr Usyk has admitted he doesn't know when he will return to the ring after Russia invaded his native Ukraine.
Usyk is due to meet Anthony Joshua for a second time this summer in a rematch of last year's world title fight.
Usyk dethroned Joshua in London to become the unified heavyweight world champion and is contracted to a second meeting with the Brit.
But Usyk is now hunkered down in Ukraine as Vladimir Putin's troops continue their assault on their neighbours.
And of a potential return date, he told CNN: "I really don't know when I'm going to be stepping back in the ring. My country and my honour are more important to me than a championship belt."
Joshua's promoter Eddie Hearn said last week that he didn't expect the fight to be delayed and that he hoped to announce a date within the next two weeks.
But Usyk's comments suggest the return bout could be pushed into late summer at the earliest.
The former undisputed cruiserweight world champion had been in London with his manager but later returned to Kiev.
He spoke to CNN from his basement as he told of how war was raging around him.
"The bombing around is crazy," he added. "They just bombed the city of Mariupol, one of my friends got a rocket in his roof. [The Russians] are not playing games."
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Usyk was previously pictured dressed in military clothing and armed with a gun.
He was also forced to deny he had fled his country when he was pictured in the UK.
"Dear Ukraine and dear Ukrainians, some wrote about me running away. Not true, I had a work trip and now I’m back. I’m home," Usyk said in a video posted to social media.
"Friends, we need to unite together and overcome this, because we are faced with exceptional difficulties.
"I’m very overcome with emotions and I’m very concerned for my country and for our people. Friends we must stop this war and we must do it together."
