For the second consecutive year, Muchova's campaign was ended by Iga Swiatek in the round of 16 as the six-time Grand Slam winner claimed an impressive 6-2, 6-0 win, winning ten consecutive games in the process.
"I felt I was playing better and better, just great," Swiatek said in her on-court interview.
"I love playing here, I love the conditions. I started to understand them a bit better a couple of years back, and since then, it feels like I can really use my advantages here. It's a great place to play tennis, hopefully I can keep doing that until the end."
Swiatek will face old rival Elina Svitolina in the last eight. Svitolina led Katerina Siniakova 6-1, 1-1 when her opponent threw in the towel.
Meanwhile, Sonay Kartal retired during her match against Rybakina, with the Australian Open champion leading 6-4, 4-3 at the time.
"Definitely not the way I wanted to finish the match," Rybakina said afterwards.
"And of course, speedy recovery. It's not easy, these kinds of injuries. It was a tough match anyway, but I'm happy that I'm going through to the next one."
Elsewhere, the 12th-seeded Belinda Bencic was beaten 6-3, 7-6(5) by Jessica Pegula, who books a last-eight date with Rybakina.