Reigning Wimbledon champion Rybakina became the player to watch at Melbourne Park after ousting world No.1 Iga Swiatek in the fourth round in two tight sets 6-4 6-4.
Latvia's Ostapenko, who won the French Open in 2017, was similarly ruthless in her 7-5 6-3 upset victory over world No.7 Coco Gauff.
Both boasting big serves and booming groundstrokes, Kazakh Rybakina says she will need to be at her most aggressive to stop world No.17 Ostapenko.
"She hits really hard, and she plays aggressive like me," Rybakina said.
"So for sure I need to be really focused on my serve because today on one side I was struggling a bit.
"It's not easy if my weapon is not going."
Rybakina is seeded 22 but didn't receive any ranking points for last year's grass court triumph after the playing tours withheld points following the All England Club's ban on entries from Russia and Belarus.
The 23-year-old feels she is capable of reaching the top ranking.
"For me I think it's still many things to improve," she said.
"If I perform like I did this week and it's going to be consistently for sure, I will say that I can be No. 1, I can beat anyone.
"For now I need to find my consistency."
Ostapenko leads Rybakina 2-0 in previous meetings, winning their most recent clash in the semi-finals of the 2021 Eastbourne International.
The 25-year-old is in the quarter-finals at a slam for the first time since her 2018 Wimbledon semi-final appearance while her previous best in Melbourne is the third round.
Ostakpenko feels comfortable about taking on Rybakina.
"With the good players I think I have nothing to lose, and I'll just enjoy it as much as possible," she said.
"It's great to be in the quarter-finals and if I play my game, I think I have all the chances.
"Of course, it's going to be a hard match against Elena, but we played a couple of times, and I know how to play against her.
"I'm just going to try to focus more on myself and on my game, and hopefully I can bring the good and aggressive game again."
The winner will play either third-seeded American Jessica Pegula, the highest-ranked woman left in the draw, or two-time champion Victoria Azarenka in Thursday's semi-finals.
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