Oleksandr Usyk says his country and honour are more important than any fight in the ring as he prepares to defend his hometown of Kyiv against invading Russian forces.
"There is no fear, absolutely no fear," he told CNN.
How could this be in the 21st century?
Usyk, who was speaking via video call and an interpreter from a basement in Kyiv, said he did not know if there was any chance of him fulfilling a planned May rematch with Joshua.
He said that he didn't know when he would return to the ring.
My country and my honor are more important to me than a belt.
Usyk has previously called on the Russian people to resist the war and for the president to engage in peace talks without preconditions.
Several former and current Ukrainian boxers have come to the defense of their homeland.
A three-weight world champion who has won over Britons on his professional record as well as two Olympic golds from his time as an amateur, has also taken up arms.
The brothers Vitali and Wladimir are in the same city.
Wladimir joined the military reserve of the city last month, while Vitali has been mayor for the last three years.
Vitali said there was a huge movement for civil defence in the city.
We are fighting for democracy and our choice, and I am proud of our men and women who are ready to defend our country.