Konstantin Koltsov, a Belarusian former professional hockey player, was 42 years old.

The news was announced by Salavat Yulaev, the Russian hockey club that Mr Koltsov played for and later worked for as an assistant coach.

"It is with deep sorrow that we inform you that the coach of Salavat Yulaev, Konstantin Koltsov, has passed away," a statement by the team said on Tuesday.

His cause of death has not been released.

The club described him as a "strong and cheerful person" who was "loved and respected by players, colleagues and fans".

The statement added: "Konstantin Evgenievich forever wrote himself into the history of our club.

"May he rest in peace."

Mr Koltsov played for the Belarus national hockey team in the 2002 and 2010 Winter Olympics - and spent parts of three seasons with the Pittsburgh Penguins, in the National Hockey League, between 2002 and 2006.

Renowned for his speed on the ice, Mr Koltsov played for Salavat Yulaev when they won the Russian Super League in 2008.

He was first linked to Sabalenka - currently ranked world number two by the Women's Tennis Association - in June 2021, according to People magazine, and the pair have frequently posted pictures together on social media.

In an Instagram post in April last year, Sabalenka, 25, posted a birthday message to Mr Koltsov, writing: "You are my dearest person, my best friend and my strongest support.

"I hope we will have everything we planned. I love you."

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Mr Koltsov was also seen supporting Sabalenka after she won her second consecutive Australian Open title in January, defeating China's Zheng Qinwen to take the crown.

Last week, the Belarusian lost in the last 16 at Indian Wells following defeat to Emma Navarro. She is scheduled to play her first match at the Miami Open on Friday.

It is unknown if she will continue in the tournament or not.