Russia invaded Ukraine and began a war on Thursday, the biggest nightmare for boxer Viktor Postol. The super lightweight contender is slated to fight Gary Antuanne Russell Saturday (10 p.m. ET, Showtime) at The Cosmopolitan in Las Vegas.

Postol is from Ukraine and left his wife, Olga, and twin sons Timothey and Lukyam, at their home in Brovary, near Kyiv.

He had told Yahoo Sports earlier in the week that he’d been trying to avoid the news so he could focus on his fight, while also hoping that a diplomatic solution was found.

But Russian President Vladimir Putin ordered his military to attack Ukraine and reports quickly emerged that the Russians had taken the airport in Kyiv, as well as the former nuclear power plant in Chernobyl.

Postol said he spoke to his wife on Thursday.

“Everything is good for them at this time,” Postol told Yahoo Sports Thursday after learning of the onset of the hostilities. “Obviously, it is not good and, mentally, it’s difficult [to prepare for the fight]."

At this stage, there isn’t much Postol can do so he plans to go forward with the fight. Going home is a different story. He said he wasn’t sure, but said he thought he’d fly to Poland and then either drive or walk across the border into Ukraine.

He said he didn’t feel in jeopardy from Russian military because of his status as a prominent athlete and a former world champion boxer.

“I honestly don’t think so,” he said. “I’m just a regular Ukrainian person. I don’t live in a fancy villa and have crazy expensive stuff, so I don’t think they’ll look at me any differently than anyone else.”

Klitschko: 'Destruction and death come upon us'

One former boxer who clearly is in jeopardy is ex-heavyweight champion Vitali Klitschko, who is the mayor of Kyiv. In an interview with Good Morning Britain, Klitschko said he was going to join the armed conflict himself.

Asked if he’d take up arms and fight in the streets to defend his country, Klitschko said, “I don’t have another choice. I have to do that.”

His younger brother, Wladimir, has said he, too, will join the fight. He made a post on various social media outlets in which he criticized Putin and said he knows the Russian people don’t want war.

“Putin makes it clear that he wants to destroy the Ukrainian state and the sovereignty of its people,” Wladimir Klitschko wrote. “Words are followed by missiles and tanks. Destruction and death come upon us. That's it, blood will mix with tears. The Ukrainian people are strong. And it will remain true to itself in this terrible ordeal. A people longing for sovereignty and peace. A people who consider the Russian people their brothers. It knows that they basically do not want this war.

“You can do something by mobilizing and organizing huge demonstrations. Make your voice heard. Make the voice of democracy heard. Say it loud and clear that international law and democracy are under attack, that war is the greatest evil and that life is sacred.”

IBF-WBA-WBO heavyweight champion Alexander Usyk left Glasgow, Scotland, where he was prepared to watch the undisputed super lightweight title fight on Saturday between Josh Taylor and Jack Catterall, and flew to Ukraine.

He released a video on social media of himself speaking in Russian with the caption on the post in all caps, “NO WAR.”

Former world champion Vasiliy Lomachenko, a two-time Olympic gold medalist for Ukraine, posted a heartfelt message on his Instagram account.

He entitled his post, “Prayer for the peace of the whole world and the enlightenment of the peoples of the Earth.”

He wrote, “Lord, grant Your peace to Your people. Lord, grant to Your servants Your Holy Spirit, so that He warms their hearts with Your love and guides them into all truth and goodness.”