Top seed Muguruza made a strong start against the French Open champion, but ultimately fell to a 1-6 6-3 6-2 defeat - a first for the Latvian against her Spanish opponent.
It was not a good day for the other Pliskova sister, though, with top seed and defending champion Kristyna beaten 7-6 (7/5) 6-1 by Kurumi Nara in the second round of the Tashkent Open.
"I think she played very aggressively", Muguruza said.
Barty is also into the Wuhan doubles semifinals (with Casey Dellacqua). Muguruza, perhaps buoyed by her performance in the first set, was able to break back and even up proceedings at 3-3, though the Spaniard was no longer playing as well as she had in the first set and was immediately broken once again.
The lone seed still standing will face red-hot Australian Ashleigh Barty for a spot in the final.
I want to pick Ostapenko in this match, but I can't based on how she served in her last match.
Barty, ranked 37th in the world, failed to convert three match points in the third set but dominated the deciding tiebreak to bag her first ever win against a top-five player. "I think she was playing just little bit better today", concluded Pliskova. "The second set I didn't play well".
"I felt like I was close", said Pliskova in her post-match press conference. I will try to recover as fast as I can today and hopefully I can play good tomorrow.
Caroline Garcia defeated No.7 seed Dominika Cibulkova, 6-3, 7-5, to make it to the last eight of the tournament, where she will face Russian Ekaterina Makarova. In the victory, Muguruza won 64 percent of her first serve points and 54 percent of her second serve points. "I was very motivated and worked very hard previous year to get back to where we are now".
A brief pause to dry the courts following a rain shower couldn't save Muguruza, and Linette served the set out to love in the next game.
The World No.88 has a history of peaking in Asia, though - and this year has been quietly putting together one of the finest stretches of her career to date.