World No.1 Karolina Pliskova needed just 46 minutes to defeat American Jennifer Brady 6-1 6-0 at Arthur Ashe Stadium and punch her ticket to the quarter-finals at the US Open.

After facing a match point during her third-round battle against Zhang Shuai on Saturday, Pliskova was never pushed by Brady, who failed to find her groove.

Brady struggled mightily with her service game, where she was only able to connect on 39 per cent of her first serves compared with Pliskova’s 67 per cent.

Brady also struggled to read Pliskova’s powerful serve and failed to convert either of her two break point chances.

“I think she was a little bit nervous,” Pliskova said.

“It was her first time on Ashe so I tried to take advantage of that.”

Next up for Pliskova is 20th-seeded American CoCo Vandeweghe, who reached her first US Open quarter-final by beating Lucie Safarova 6-4 7-6 (2).

Vandeweghe is the third American woman into the quarter-finals at Flushing Meadows this year, joining Venus Williams and Sloane Stephens, who won their fourth-round matches a day earlier.

Madison Keys could raise the total to four by winning her fourth-rounder later on Monday.

Meanwhile, Kaia Kanepi has beaten Russian Daria Kasatkina 6-4 6-4 to become the first qualifier in 36 years to reach the US Open women’s quarter-finals.

The 32-year-old Estonian is ranked 418th after missing much of the past two years with problems in the soles of both feet and a virus known as a precursor to mononucleosis.

Kanepi was able to get into the qualifying event by virtue of a protected ranking.