Pliskova, runner-up at Flushing Meadows last year, would have lost her world number one ranking had she been beaten on Arthur Ashe Stadium but instead moved another step closer to a first career grand slam title.
Chinese Zhang was the more aggressive player from the start, frequently rushing to net and stepping into the court to attack Pliskova's second serve on an unseasonably cool day in New York.
The strategy paid off as she broke Pliskova in her first two service games to take a 3-1 lead and captured the first set with an emphatic overhead smash.
She continued her fiery play into the second set but on match point tightened up and hit an errant backhand, disappointing a New York crowd that had been rooting for the underdog.
Pliskova won the next three games to close out the set.
Zhang did not roll over, however, and broke Pliskova to take an early 2-0 lead in the third but Zhang's mistakes soon started piling up.
Zhang ended the contest with 46 unforced errors to Pliskova's 38.
She was also undone by the tall Czech's biggest weapon - her powerful serve.
Pliskova finished with nine aces and just one double fault while Zhang hit two aces while committing five doubles.
Pliskova needed an injury time out to attend to a sore arm between the second and third sets, which she said she hopes will not bother her when she faces either American Jennifer Brady or Monica Niculescu of Romania in the fourth round.
"I will have to improve in the next one," the 25-year-old Pliskova said in a courtside interview.
"Hopefully, it's nothing serious and I'll be ready for my next match."
Pliskova said that while she may appear stone-faced on the court there are plenty of emotions running through her veins.
"I don't really feel calm," she said.
The contest was 25-year-old Zhang's best showing against the tournament's top seed but she is now winless in five matches against Pliskova.
(Editing by Ed Osmond)
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