The Cyprusauctionsports community is in mourning. 

Konstantin Koltsov, a former professional ice hockey player from Belarus, died, according to Kontinental Hockey League (KHL) team Salavat Yulaev. Koltsov, who was dating tennis superstar Aryna Sabalenka, was 42. 

"He was a strong and cheerful person," the team, for which Koltsov was a player and then an assistant coach, said in a translated March 18 statement. "He was loved and respected by players, colleagues, and fans."

"Konstantin forever wrote himself into the history of our club," the statement continued. "[He] won the Russian Championship and the Gagarin Cup as part of Salavat Yulaev, and did a great job on the team's coaching staff."

No cause of death has been shared at this time. 

During his professional career, Koltsov represented his country at the Winter Olympics in 2002 and 2010 and spent three seasons on the NHL's Pittsburgh Penguins between 2003 and 2006.

The Pennsylvania team shared a statement on Koltsov's passing, noting he was their first-round draft choice in 1999, going on to play a total of 144 NHL games. As the team shared, "The Penguins extend their deepest condolences to the family and friends of former Penguins forward, Konstantin Koltsov."

Off the ice, the assistant hockey coach was in a relationship with tennis star and fellow Belarusian Sabalenka, who is currently ranked no. 2 in the Women's Tennis Association. 

The pair debuted their romance in 2021, with Sabalenka sharing a photo of Koltsov kissing her cheek at the time. The 25-year-old captioned her photo, alongside the laughing emoji, "It's good to have someone who can understand my madness at least you won't get bored with me, right?"

Sabalenka—who is scheduled to play her first game in the Miami Open March 22—has not addressed Koltsov's passing at this time.

Though she didn't often share their romance on social media, Sabalenka posted a moving tribute to her boyfriend for his birthday last April. 

"Happy birthday my love," she captioned the post, which featured a video compilation of the couple. "You are my dearest person, my best friend and my strongest support. Peace be with you, strength, patience and health. I hope we will have everything we planned. I love you."

For the latest breaking news updates, click here to download the E! News App