Defending champion Sabalenka held off big-hitting 45th-ranked American Hailey Baptiste 6-4, 6-4 while Rybakina beat fifth-seeded American Jessica Pegula - runner-up to Sabalenka last year - 2-6, 6-3, 6-4.
They will return Thursday night at Hard Rock Stadium - home of the NFL's Miami Dolphins - to fight for a place in the final of the elite ATP and WTA event.
Rybakina beat Sabalenka in a nail-biting Australian Open final in January - the world number one's only defeat in 2026 - but the Belarusian avenged it with a victory in the Indian Wells final this month.
"We've been playing a lot of matches, recently actually, and all of them have been a battle, all of them been a show," Sabalenka told the Tennis Channel. "I'm super-excited facing her."
Sabalenka is now two wins away from completing the "Sunshine Double" of Indian Wells and Miami.
Baptiste, playing her first WTA 1000 quarter-final, failed to convert three break points in Sabalenka's first two service games.
Sabalenka finally broke Baptiste when the American double-faulted on set point.
Sabalenka gained an early break in the second, but Baptiste broke back and held confidently to level at 4-4.
But as she served at 4-5 to stay in the match, the American opened with three straight double faults. Sabalenka pounced, converting her second match point with a blistering return.
Familiar foes
"She really pushed me," Sabalenka said.
"The rhythm, the heaviness of her shots is incredible. I'm super happy that I was able to hold the pressure and to get the win."
She'll now face a familiar foe in Rybakina, who shrugged off a slow start to post her fifth straight win over Pegula - a streak that includes a semi-final victory at the Australian Open and a quarter-final win at Indian Wells.
Reigning Australian Open champion Rybakina, a 26-year-old from Kazakhstan, fired 12 aces in beating the American, last year's Miami runner-up, for their fifth consecutive meeting.
Rybakina improved to 6-3 all-time against Pegula, including an Indian Wells quarter-final and semi-finals of the Australian Open and last year's WTA Finals on the way to titles.
"It's always very difficult matches with Jessica," said Rybakina, who is seeded third despite rising to No. 2 in the world for the first time this week.
"She started playing well, and I was a bit rushing and frustrated, but I'm happy that I managed to bounce back and turn it around in the second set."
Pegula, who won last month's WTA title in Dubai, broke twice to begin the match with a 4-0 lead when Rybakina netted a forehand in the opening game and sent a forehand long in the third.
Pegula held twice more to take the first set in 35 minutes when Rybakina netted a backhand, the American making only two unforced errors in the opening set.
Rybakina missed three overhead smashes in the fifth game of the second set but held serve then broke when Pegula swatted a forehand long for a 4-2 edge on the way to forcing a third set.
Rybakina broke Pegula to open the third set and stayed in command to advance after two hours and 15 minutes.