Karolina Pliskova saved a match point as she came from a set down for the second successive round to overcome a valiant effort from Zhang Shuai and reach the US Open last 16.
The world number one fought back after losing the first set against Nicole Gibbs in the second round but was pushed even further by 27th seed Zhang before prevailing 3-6 7-5 6-4 after two hours and 19 minutes.
Zhang was on the verge of a huge shock win when she had match point at 5-4 in the second.
However, the Chinese cracked under the pressure and allowed Pliskova to force a decider. Zhang again broke at the start of the third, but it was Pliskova's resilience that won the day as the Czech set up a fourth-round clash with either Jennifer Brady or Monica Niculescu.
It appeared as if Pliskova was set to make short work of Zhang when she quickly went 40-0 up in the opening game and secured an immediate break.
However, Zhang responded by rattling off the next three games and then saved two break points to hold for 4-1, showcasing outstanding movement at the net to move into a commanding lead.
Her prowess at the net helped her wrap up the opening set with a forehand smash, but Pliskova looked to have found her rhythm in the second as she powered into a 3-0 lead.
Zhang's spirit again came to the fore, though, with the next three games going her way to level the set.
A superb Pliskova backhand down the line prevented Zhang from making it four on the spin but an unforced forehand error gave the world number 26 the chance to serve for the match at 5-4.
But the match point was squandered as the nerves became too much for Zhang, who hit long to surrender a break. Pliskova then saved three break points to hold for a 6-5 lead, with a forehand pass and a superb return of a Zhang second serve giving her the foundation to break to force a decisive set.
Another advantage was quickly surrendered by Zhang to start the third as she gave up a 2-0 lead, but she continued to display great spirit by saving a break point to hold for 3-3.
Yet the pressure finally told when Zhang served to stay in an engrossing encounter. A seemingly simple forehand was sent into the net to set up a match point that the now ruthless Pliskova dictated, sealing an extremely hard-fought win with a rasping cross-court backhand.
Pliskova  bt Zhang 3-6 7-5 6-4
Pliskova - 33/38
Zhang - 33/46
Pliskova - 9/1
Zhang - 2/5
BREAK POINTS WON
Pliskova - 6/12
Zhang - 5/17
FIRST SERVE PERCENTAGE
Pliskova - 63
Zhang - 61
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Pliskova - 57/55
Zhang - 58/51
Pliskova - 108
Zhang - 105