The 62-year-old Portuguese coach Fernando Valente has revealed Georgiy Sudakov's story during Russia's invasion of Ukraine.
The footballer, who worked under Valente at Shakhtar Donetsk, is having to hide in a bunker with his pregnant girlfriend during the war.
"Georgiy Sudakov is the greatest talent I've ever coached," Valente said in a post on Facebook and Twitter. "He's 19 years old, a Ukraine international and he recently renewed his contract at Shakhtar until 2026.
"He's a fantastic human being and waiting to become a father with his partner, Lisa.
"He has dreams to fulfil, but they've been snatched away and he's now in a bunker during a senseless war. I cry for this couple and for all of the young players and friends I've left behind in a Ukraine that gave me happiness for two years.
"My heart is broken."
Who is Georgiy Sudakov?
Sudakov was impressing as an attacking midfielder for Shakhtar before Russia invaded Ukraine, and he has three caps for his country.
"Sudakov has enormous potential," Valente said. "He could play for Barcelona or Manchester City.
"He's the best talent I've trained and I had one of the strongest connections I've had with him.
"I have a photo of him and his girlfriend, who is pregnant, on my phone. They're so happy.
"He recently sent me a photo of them stuck in a bunker. Every time I see it, tears fill my eyes."