Aryna Sabalenka expressed deep sorrow, stating her "heart is broken" following the passing of her ex-boyfriend Konstantin Koltsov.

Koltsov, a former NHL player for the Pittsburgh Penguins, tragically died in Miami at the age of 42 in what authorities have described as an "apparent suicide."

Sabalenka, who is set to compete in the Miami Open this week, clarified on Wednesday via an Instagram story that she and Koltsov had ended their relationship before his passing.

"Konstantin's death is an unthinkable tragedy and while we were no longer together, my heart is broken," Sabalenka wrote. "Please respect my privacy and his family's privacy during this difficult time."

Sabalenka was pictured practicing in Miami ahead of her first outing against best friend Paula Badosa, who admitted facing the Belarusian will be "uncomfortable."

Badosa said of Sabalenka: "Yesterday, I spoke with her for a long time. This morning, the same. So I know what she's going through. I know the entire situation and what is happening.

"It's a little bit shocking for me to go through that because, in the end, she's my best friend, and I don't want her to suffer. It's a very tough situation.

"At the same point, playing against her is also uncomfortable. But I don't really want to talk about it because I said I'm not going to. She's my best friend, and I promised that.

"She's a strong woman. I think she will get the power from somewhere. I hope it's going to be a battle, a good match."

Caroline Wozniacki became emotional talking about the situation during her press conference, with the Dane saying: "I can't even imagine what she's going through right now.

"I'm also tearing up. It's such a terrible situation. It's so hard. I reached out to her and told her I was here if she needed anything.

"I love Aryna. I think she's such a great person. She's always so happy and out there. To see her go through that, it's heartbreaking.

"Everyone grieves in a different way. She was walking past today. I was giving her her space. I told her that if she ever needs anything, I'm here, we're here for her."

Koltsov had been a regular presence, supporting Sabalenka at tournaments. The news was announced by the Russian ice hockey team Salavat Yulaev Ufa, where Koltsov had been an assistant coach.

A statement on the club's website read: "It is with deep sorrow that we inform you that Salavat Yulaev coach Konstantin Koltsov has passed away. He was a strong and cheerful person, loved and respected by players, colleagues, and fans.

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

"The hockey club Salavat Yulaev expresses its condolences to the family and friends of Konstantin Evgenievich Koltsov."

It is the second tragedy to hit 25-year-old Sabalenka, whose father Sergey, also a former ice hockey player, died in 2019 at the age of 43.