Usyk flew into London last week to watch Chelsea beat Lille on Tuesday night and visit Sheffield on Wednesday.
He also met with Joshua’s promoter Eddie Hearn for talks on a date and venue for the heavyweight rematch.
But the fearless southpaw returned straight back into the warzone and posted a string of emotional videos to Putin and the invading Russian hordes, before finally arming himself on Monday.
The AJ rematch, which Hearn has been hoping to stage in late May or early June, now seems certain to be delayed.
Married father-of-three Usyk clearly has far more important things on his mind and he has appealed directly to the Russian people for help.
I’ve learned sports and politics go hand in hand. They are powerful voices and it is good they are speaking up.
Anthony Joshua
In an Instagram video, he said: “Good morning to everybody. My name is Oleksandr Usyk. I’d like to speak to the people of Russia.
“If we consider ourselves as brothers, Orthodox ones, do not send your children to our country, do not fight with us.
“Also I’m addressing this to the President, Vladimir Putin. You can stop this war.
“Please just sit down and negotiate it with us without claims. Our kids, wives, grannies are hiding in the basements.
“We are here in our own country, we cannot do it any other way. We are defending. Stop this war, stop it. No War.”