Sabalenka is the only player still alive in either draw who reached the final four in Flushing Meadows last year. She lost to runner-up Leylah Fernandez in the semifinals.
The No. 6 seed from Belarus will face top-ranked Iga Swiatek for a spot in her first Grand Slam final.
"I'm ready for it,'' Sabalenka said. "I'm ready for another fight.''
She reached her only other major semifinal last year at Wimbledon, where Pliskova beat her before falling to Ashleigh Barty.
Sabalenka quickly showed this matchup would be much different, racing to a 4-0 lead against the 2016 US Open runner-up and wrapping up the first set in 28 minutes.