In the first match of the day on Grandstand court Sabalenka was scheduled to face good friend Paula Badosa in a second round encounter after receiving a first round bye.
The Belarusian issued a brief statement on Wednesday saying her "heart was broken" by the "unthinkable tragedy" but has otherwise remained out of the spotlight.
The statement was also the first mention since the tragedy that the couple had split.
The Miami-Dade police department confirmed on Tuesday that they had responded to a call the day before at a Miami resort about reports of a man jumping off a balcony. The police said no foul play was suspected.
Koltsov, 42, played for the Belarus national team at the 2002 and 2010 Olympics and spent parts of three seasons with the National Hockey League's Pittsburgh Penguins between 2003 and 2006.
The news of Koltsov's death sent a shockwave through the Miami Open as Sabalenka's fellow players rallied around her, including her opponent Badosa.
Badosa set up the meeting with the player she called her best friend on Tuesday with a win over two-time Grand Slam winner Simona Halep, who was making her return to competition following a doping suspension.
"It's not an easy challenge, it's a mental one," said Badosa about facing two-times Australian Open champion Sabalenka. "I know the entire situation, what is happening.
"That for me is a little bit shocking also to go through that because at the end she's my best friend and I don't want her to suffer."
The chances Sabalenka or anyone else getting on the Hard Rock stadium complex courts on Friday appeared unlikely with the forecast calling for steady and sometimes heavy rain and thunderstorms through into early Saturday.
Play was to begin at 11am ET (16:00 CET) but has already been pushed back an hour twice with the earliest start now 1pm ET (18:00 CET).
The rain comes at the worst possible time as the tournament hits the weekend with a full slate of big names scheduled to make their first appearances, including women's world number one Iga Swiatek and defending men's champion Daniil Medvedev along with home favourites Coco Gauff and Taylor Fritz.
