Johanna Konta avenged her Rome final loss to Pliskova in May, beating the Czech third seed for just the second time in eight tries, 6-7 (1/7), 6-3, 7-5.
The British 16th seed has raised her game at the Slams this season, and is enjoying her best run at Flushing Meadows, having twice reached the fourth round.
“To go one step further is a massive achievement for me and I’m really hoping to make that one, two, three steps forward,” Konta said.
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Konta has experienced middling fortunes on the WTA circuit this year while producing some of her best tennis at the majors, reaching the semi-finals at Roland Garros and then advancing to the last eight at Wimbledon.
“To make the quarter-finals of a Grand Slam for the third time this year is a massive achievement for me,” she said.
Pliskova, the 2016 US Open runner-up, saw her hopes of returning to world number one this fortnight extinguished by the loss.
Ukrainian fifth seed Elina Svitolina advanced to her first US Open quarter-final with a 7-5, 6-4 victory over 2017 runner-up Madison Keys.
“I’m very happy because I was always playing well here but never went past the fourth round,” said Svitolina, whose best Slam showing was her run to the Wimbledon semi-finals in July.